Applying the Public Health Approach to Prevent Targeted Violence in the United States

Abstract

Objective:

Targeted violence (i.e., violence against a preidentified target intended to influence the broader population and/or generate publicity for the perpetrator or their grievance) is a national security threat and an urgent public health problem affecting individual and community well-being. Drawing on decades of experience and examples from the U.S. Centers for Disease Control and Prevention and the public health field, this article illustrates how the four-step public health approach to violence prevention (i.e., define and monitor the problem; identify risk and protective factors; develop and test prevention strategies; ensure widespread adoption) can be applied to accelerate advancements in evidence-based practice for the primary prevention of targeted violence.

Method:

In this narrative review, examples of risk and protective factors and evidence of what works to prevent violence and suicide are compared with the targeted violence literature to identify shared risk and protective factors, promising prevention approaches, and key research gaps.

Results:

This article highlights opportunities to enhance consistency in measurement and expand public health data systems, identifies an initial set of 20 shared risk and protective factors, highlights evidence-based violence and suicide prevention approaches with potential for preventing targeted violence, and suggests focus areas for advancing research. Select ongoing efforts by the Department of Homeland Security illustrate the public health model in action.

Conclusion:

Applying the Centers for Disease Control and Prevention’s public health approach to violence prevention can bridge efforts by the Centers for Disease Control and Prevention, Department of Homeland Security, and communities to build a violence prevention infrastructure connecting science and action across multiple forms of violence, including targeted violence.

Evidence of a rise in domestic violent extremism in the United States (U.S.; Department of Homeland Security [DHS], 2024b; Wray, 2021, 2024) and concerns about racially and ideologically motivated mass violence incidents (Clifford, 2021; Office of the Director of National Intelligence, 2021) have prompted growing attention and urgency from policymakers and communities looking for new approaches to prevent these forms of violence, referred to here under the collective term targeted violence. In recent years, these calls—and responses to them at the federal, state, and local levels—have increasingly focused on the application of a public health-focused approach to this problem (National Security Council, 2021). Discussion of applying public health principles and models to counterterrorism began more than a decade ago and was addressed by the U.S. Department of Homeland Security (DHS) in a 2017a research agenda on countering violent extremism (Bhui et al., 2012; DHS, 2017a). Yet, there remains limited agreement on the ways in which public health data, research, practice, and systems can best inform the development and implementation of effective approaches to prevent targeted violence, including domestic terrorism (e.g., Byington, 2019; Challgren et al., 2016; DHS, 2024a; Eisenman & Flavahan, 2017; Garcia, 2019; McCulloch et al., 2023; Weine et al., 2017; Wynia et al., 2017).

To help advance research and action on this urgent threat to public health and national security, this article draws on four decades of experience with violence prevention research and practice at the U.S. Centers for Disease Control and Prevention (CDC)’s Division of Violence Prevention to outline a framework for the primary prevention of targeted violence in the United States. Applying CDC’s four-step public health approach to violence prevention, we highlight areas in which the field of targeted violence may benefit from and build on lessons learned from prevention research on other forms of violence and suicide, identify key areas of focus for building a public health research agenda for the primary prevention of targeted violence, and seek to engage violence prevention researchers and practitioners in building the evidence base for targeted violence. In addition, we share examples of ongoing efforts by DHS Science and Technology Directorate and Center for Prevention Programs and Partnerships (CP3) to apply the public health approach by building and bridging the research and practice communities to inform and implement targeted violence prevention.

Historical Context

The application of a public health approach to the prevention of targeted violence represents a significant shift in focus from the initial eras of research and practice. Post-9/11 counterterrorism efforts in the United States focused primarily on promoting national security through intelligence and law enforcement infrastructure and practice to combat threats from foreign terrorist organizations (e.g., DHS, 2010; Guler & Demir, 2024). By 2011, these efforts expanded into a broader national strategy—termed countering violent extremism—focused on intervening with high-risk individuals and partnering with local communities to detect and report concerning behavior to disrupt pathways to violent radicalization (DHS, 2017b; The White House, 2011; Weine et al., 2017). However, implementation of the strategy was challenging due to inconsistency in the definitions and operationalization of countering violent extremism across agencies and changes in federal leadership over time (Challgren et al., 2016). Further, some countering violent extremism approaches were met with criticism from community and civil rights organizations concerned about the stigmatization and surveillance of marginalized groups, particularly in Muslim communities (Aggarwal, 2019).

In response to these challenges, as well as shifts in the threat landscape, the U.S. government pivoted to an approach focused on providing community engagement and education, partnerships, and training to all communities—rather than focusing on select ideological groups or contexts—in order to identify, disengage, and support individuals at risk for violent extremism, an approach termed preventing violent extremism (Stephens et al., 2021; Wray, 2021). In 2019, DHS implemented the Strategic Framework for Countering Terrorism and Targeted Violence, including funding for national efforts to increase awareness and strengthen societal resistance to the drivers of violent extremism (Department of Homeland Security and Federal Bureau of Investigation, 2019). This framework also expanded DHS efforts from a sole focus on terrorism to include other forms of targeted violence, such as school shootings, supported by the findings and recommendations of a 2019 DHS-funded review of prior U.S. terrorism prevention efforts (Jackson et al., 2019).

While efforts to prevent attacks by foreign terrorist organizations remain critical to national security, rises in domestic violent extremism within the United States have raised additional concerns about the impact of these threats on the safety and health of Americans (National Security Council, 2021). In 2020, for example, DHS identified racially or ethnically motivated violent extremism as the “most persistent and lethal threat” in the United States (DHS, 2020, p. 18). In 2023, the Federal Bureau of Investigation reported that domestic terrorism investigations had more than doubled since 2020 (Wray, 2023), with racially or ethnically motivated violent extremism and antigovernment/antiauthority violent extremism continuing to pose a primary threat (Wray, 2023). This shift in focus has been accompanied by a growing interest in, and demand for, early (or, “primary”) prevention efforts focused on working “upstream” to prevent the risk for violent extremism from developing in the first place, incorporating the language and ideas of prevention and public health into this work (DHS, 2024a; McCulloch et al., 2023; Wolfowicz et al., 2020b). Within the United States, this shift has been most evident in the launch of DHS CP3 in 2021. CP3 expanded a grant program supporting local prevention efforts, placed regional prevention coordinators around the country to build partnerships and facilitate program development, and adopted a “public health-informed approach” with the goal of building capacity for evidence-based targeted violence prevention in the United States, including primary prevention (DHS, 2024a). A focus on primary prevention—or preventing violence before it begins—is a key tenet of the well-established public health approach to violence prevention, which has been applied to advance research and practice on other forms of violence since the 1990s (Hammond et al., 2006), and provides a unique and complementary approach to historical efforts to address the threats of targeted violence, including violent extremism, through security-based and responsive interventions.

What Is Targeted Violence?

Terms and definitions in the fields of violence prevention and counterterrorism vary substantially across time and purpose, including the use of the term targeted violence (Deflem, 2020; Hamby, 2017; Hunter et al., 2021; McBride et al., 2022). These differences often reflect the specific cultural, legal, practical, or temporal context in which the terms or definitions are being used, and as such, consistency across purposes and over time may be impractical and unlikely. However, clear constructs and definitions also provide a critical foundation for science (Hamby, 2017) and are a necessary first step in public health research (Dahlberg & Krug, 2002; see Figure 1). Precise, consistent definitions can provide a shared understanding, differentiate between subtypes of violence with potentially unique etiologies and prevention strategies, standardize measurement for research and public health surveillance,¹ and allow for consistent evaluations of prevention and intervention efforts (Hamby, 2017). Further, the terms and definitions applied to a problem influence the way the problem is viewed and addressed by society and across sectors. For example, Garcia (2019) noted that a shift in the language of “countering” to “preventing” violent extremism not only reflects an actual change in strategy but also conveys to the public an increased focus on proactive versus reactive efforts.

Figure 1. The Public Health Approach to Violence Prevention.

Note. See the online article for the color version of this figure.

To help clarify the use of the term targeted violence relative to other common terms and definitions and ground discussion of this problem from a public health perspective, Figure 2 outlines a conceptual model in which targeted violence represents an overarching category of violence that encompasses subcategories of violent extremism and terrorism and overlaps with hate crimes. This model draws on and seeks to conceptually organize differing terms and definitions utilized across the field to support the movement toward uniform definitions in research and provides the foundation for measurement precision (Aryaeinejad & Scherer, 2024; DHS, 2019; McBride et al., 2022; Schweppe & Perry, 2022). As is often the case in violence research (e.g., rape; Marsil & McNamara, 2016), these terms may not—and are not intended to—align with or reflect legal or official definitions utilized by the federal government or other jurisdictions, and we expect that they will continue to evolve as the literature and understanding of the problem develops.

Figure 2. A Conceptual Model of Targeted Violence and Related Constructs.

Note. See the online article for the color version of this figure.

Targeted violence, as described here, includes intentional violent acts against a preidentified individual or property based on the target’s perceived identity or affiliation, and which are intended to intimidate or coerce the broader population and/or generate publicity for the perpetrator and their grievance.² Targeted violence that lacks a clear ideological motivation falls into the broadest subcategory of general targeted violence. This includes many mass shootings in schools and workplaces, which are often identified as grievance-based and nonideological (Schildkraut et al., 2021). Violent extremism represents a subtype of targeted violence in which ideologically motivated perpetrators—through a process of cognitive and/or behavioral radicalization³—come to believe that engaging in acts of violence is necessary and justified in response to a grievance or to promote a political, religious, or social agenda.⁴ The Federal Bureau of Investigation and Department of Homeland Security (2022) have identified five categories of domestic violent extremism: racially/ethnically motivated, antigovernment/antiauthority, animal rights/environmental, abortion-related, and all other threats (including other forms of hate-motivated violence and other ideologies, such as conspiracy theories). In addition to domestic violent extremism, ideologically motivated violence that is inspired (but not necessarily directed) by the ideologies and objectives of foreign terrorist organizations or a rejection of Western culture and values is referred to as “homegrown” violent extremism.

Hate-motivated violent extremism (HMVE), as shown in Figure 2, includes acts of ideologically motived targeted violence driven by bias against the target’s perceived identity (e.g., race/ethnicity, religion, disability, sexual identity). While most, if not all, acts of HMVE could also be considered hate crimes, not all hate crimes constitute HMVE or targeted violence. Indeed, many hate crimes⁵ are impulsive and reactive, and lack the planning, organization, or intent to influence the broader population associated with targeted violence as defined here, and thus would not be considered targeted violence (Sullaway, 2016). However, hate crimes may share a similar etiology, effect on public health (e.g., psychological impact of hate crimes against Asian Americans during COVID-19; Tessler et al., 2020), and response to primary prevention approaches addressing shared risk and protective factors. Although sometimes used interchangeably with violent extremism (Sacco, 2023; Sullaway, 2016), terrorism is differentiated here as a subtype of violent extremism in which acts of violence are focused specifically on creating political or social instability to influence policy or disrupt the conduct of a government.

Two aspects of this conceptual model should be noted. First, these categories are not mutually exclusive; incidents often fall into multiple categories and are motivated by multiple ideologies, grievances, or objectives. For example, HMVE may also constitute terrorism if an objective of the violence is to create sociopolitical instability that redistributes (or strengthens) power to the in-group (Hardy & Henschke, 2024). Other threats may combine extremist ideologies, as seen in the emergence of “eco-fascism” in which groups integrate radical beliefs about environmentalism and racial and ethnic superiority to justify violence (Macklin, 2022). Second, the definitions included in this conceptual model focus on acts perpetrated in the United States by individuals influenced or motivated by domestic grievances and extremist ideologies, whether those ideologies originate domestically or internationally. Targeted violence, as defined here, excludes acts of violence perpetrated or directed by foreign terrorist organizations in the United States or abroad, including individuals who travel to the United States to perpetrate targeted violence or terrorism. In addition to legal distinctions in responsibility for global counterterrorism in the United States,⁶ the application of domestic public health and primary prevention practices may not be practical or effective for preventing the development of threats abroad. As such, the current article and public health approach are focused on identifying risk and protective factors that can be addressed by U.S. public health policy and practice and partner sectors (e.g., education, law enforcement). However, it is also important to recognize the ways in which some forms of violent extremism are increasingly connected globally through organized efforts (e.g., recruitment, alignment of ideologies or goals) and the online spread of propaganda (Gunton, 2022; Miller-Idriss, 2022). Thus, there may be potential for adapting and applying strategies developed in other countries (e.g., Bressan et al., 2024) to address related manifestations of targeted violence in the domestic context.

Targeted Violence Is a Threat to Public Health

Targeted violence is not only a national security and law enforcement concern but also a public health problem with the potential for significant immediate and long-term harm to the physical and mental health of those exposed. Currently, there is a lack of quality data to fully understand the full scope of deaths and injuries that result from all forms of targeted violence, although new data systems are in development to address this gap.⁷ While the number of deaths and injuries attributed to targeted violence represent a small proportion of overall violence-related morbidity and mortality in the United States,⁸ these high-profile incidents can have serious long-term effects on survivors, families, and communities that extend well beyond the immediate victims. For example, nationally representative data from Gallup-Heathway’s survey collected from 2008–2016 found that mass shootings reduced community and emotional well-being for at least 3 months postincident (Soni & Tekin, 2023). A review of 49 studies examining mass shooting incidents found that survivors and members of affected communities experienced increases in posttraumatic stress, depression, and other psychological symptoms, with some evidence that even indirect exposure increased fear and reduced perceptions of safety in the short term (Lowe & Galea, 2017). Another review found that youth exposed to mass shooting incidents have significant mental health effects, including posttraumatic stress, depression, substance abuse, and anxiety (Cimolai et al., 2021). Exposure to school shootings, in particular, also has harmful effects on students’ educational and economic outcomes, including high school and college graduation rates and earnings in young adulthood (Cabral et al., 2020). Research has also found that hate-motivated violence is associated with more significant psychological effects for victims than nonhate-motivated incidents (e.g., Corcoran et al., 2016). One study using data from a national, longitudinal study found that higher rates of hate crimes from 2000 to 2006 were associated with substantial increases in rates of diabetes at the state level and hypertension and obesity at the county level from 2008 to 2016 (Gero et al., 2022). Finally, in a 2019 nationally representative survey of U.S. adults, seven in 10 reported that mass shootings were a significant source of stress for them, and one-third had avoided going to certain places or events due to a fear of mass shootings (American Psychological Association, 2019). More research is needed to understand the extent of these impacts on physical and mental well-being for society at large and for those communities and groups most directly impacted. However, there is already substantial evidence that these targeted violence incidents, and the threat of these incidents, pose significant harm to public health and well-being.

Comprehensive measures of targeted violence prevalence in the United States, as defined here, do not currently exist, but available data on related measures of extremist violence, mass shootings, hate-motived violence, and school shootings may serve as proxy measures of targeted violence, capturing subtypes of targeted violence or forms of violence that overlap with targeted violence.⁹ Such data suggest these incidents are becoming more frequent and more deadly—increasing the urgency of this threat to public health and safety. For example, evidence suggests that there has been a steady rise in the number of individual and mass violence incidents originating from extremist beliefs and motivations in the United States and internationally (Jasko et al., 2022; Jones, 2018; Jones et al., 2021; Perliger, 2012). A Washington Post analysis found that the number of domestic terrorism incidents¹⁰ in 2020 (n = 73) was the highest seen in a quarter century (1994–2020; O’Harrow et al., 2021). In a recent review of 60 studies including over 18 years of public mass shooting incidents (2000–2018), the National Institute of Justice also identified a distinct upward trend in the incidence and severity of mass shootings in the United States (Kane et al., 2023). One study found that of the 167 public mass shootings over more than 50 years (1966–2019), 20% had occurred in the last 5 years (2014–2019) and more than half occurred since 2000 (Peterson, 2021). From 2020 to 2021 alone, the number of mass shooting incidents in the United States increased by 11.3%, with increases in both injuries (11.2%) and deaths (14.7%; Donnelly et al., 2023). Data from the Federal Bureau of Investigation’s Uniform Crime Reports also showed an 11.6% increase in hate crimes from 2020 to 2021 (Federal Bureau of Investigation, 2023). Finally, a study of school-associated homicides from 1994 to 2018 found that while rates of single-victim homicides in school settings remained relatively stable for more than two decades, multiple-victim incidence rates increased significantly from 2009 to 2018, with much of that increase attributed to eight incidents in the last 2 years of data collection (Holland et al., 2019). Notably, an additional 67 would-be school attacks were identified as being successfully averted between 2006 and 2018, emphasizing a need to not only disrupt targeted violence plots but also prevent their development in the first place (National Threat Assessment Center, 2021).

The Public Health Approach to Violence Prevention

The public health approach to violence prevention—developed by CDC’s Division of Violence Prevention¹¹—is rooted in four key tenets: a focus on primary prevention or preventing the risk for violence before it develops;¹² reducing population-level prevalence (as opposed to solely intervening with at-risk individuals); supporting multisectoral and multilevel prevention strategies; and leading with the science. Applied to targeted violence, this approach suggests an emphasis on the development, evaluation, and implementation of evidence-based primary prevention approaches that operate across levels of the social ecology—characteristics of individuals and the relationships, communities, and societies in which they exist (Figure 3)—to prevent the social conditions and risk factors that create vulnerability to cognitive and behavioral radicalization and targeted violence perpetration in the context of violence-supportive ideologies or grievances and build protective factors that mitigate those risks. Primary prevention strategies are intended to work in tandem with secondary and tertiary prevention efforts, including those that seek to treat injuries, enhance recovery for survivors of violence, and reduce the risk of recidivism among individuals with a history of targeted violence-related behavior. Thus, a focus on the primary prevention of violence complements, and does not replace, the critical work of the health care system, law enforcement and intelligence agencies, or multidisciplinary teams engaged in secondary and tertiary prevention to identify and respond to active threats to public safety or the needs of victims.

Figure 3. The Social Ecological Model.

Note. See the online article for the color version of this figure.

The public health approach is operationalized as four iterative steps, each of which can be applied to the problem of targeted violence to guide the development and implementation of effective primary prevention approaches. As shown in Figure 1, these steps include define and monitor the problem; identify risk and protective factors; develop and test prevention strategies; and assure widespread adoption. This approach has been applied by CDC’s Division of Violence Prevention and the larger public health community for four decades to address violence; including youth and community violence, sexual violence, intimate partner violence, child abuse and neglect; as well as suicide (Dahlberg & Krug, 2002; Mercy et al., 1993). This work has resulted in the identification and implementation of effective prevention approaches (e.g., Basile et al., 2016; Centers for Disease Control & Prevention [CDC], 2024; Fortson et al., 2016), as well as paradigmatic advancements in the practice field toward investments in primary prevention (CDC, 2019b; Decker et al., 2018; DeGue et al., 2012; Hohl et al., 2019). Although targeted violence is undoubtedly unique from other forms of violence in many respects, research has identified many shared risk and protective factors acros s other violence types (Wilkins et al., 2014). Applying the same approach used to identify and implement effective prevention approaches for those behaviors may help to accelerate evidence-based prevention of targeted violence as well. Below we discuss each of these steps and their potential application to the primary prevention of targeted violence in more detail.

Applying the Public Health Approach to Prevent Targeted Violence

Define and Monitor the Problem

The ability to define, quantify, and track a problem in a standardized and reliable manner serves as the groundwork for—and the first step of—the public health approach. As discussed above, using consistent definitions across data systems, research, programs, and policy activities helps ensure that understanding and measurement of the problem are aligned and comparable. The systematic collection of robust, population-level data on health and well-being through public health surveillance is critical to identifying populations at heightened risk, understanding the nature and scope of the problem, monitoring trends in prevalence over time, and identifying population-level risk and protective factors—all of which can be used to inform the design, implementation, and evaluation of prevention strategies. Such data may come from police reports, medical examiner files, vital records (e.g., birth, death), health care data, population-based surveys, hotline data, social media, or other sources. Without consistent definitions and ongoing data collection, prevention efforts across sectors run the risk of being disjointed and ineffective.

Over the past several decades, public health surveillance systems have been established and maintained to ensure consistent, continuous monitoring of violence-related outcomes at the population level. Among them is CDC’s National Violent Death Reporting System (NVDRS).¹³ NVDRS has collected data on the characteristics and circumstances of violence-related deaths since 2003 (Nguyen et al., 2024). Prior to the implementation of NVDRS, no single system was monitoring the prevalence and circumstances of violent deaths collectively using standardized definitions. In contrast, NVDRS uses data from multiple sources, including death certificates and investigative reports from the coroner/medical examiner and law enforcement, to capture comprehensive information about stressors and events that precipitated or contributed to homicides, suicides, and legal intervention deaths in participating jurisdictions; as of 2018, all 50 U.S. states, the DC, and Puerto Rico participate in NVDRS. NVDRS also allows for multiple victims to be linked within a single incident, such as in mass shootings. Data on the incident context, circumstances, and victim and suspect characteristics allow for a more thorough exploration of risks associated with different types of violent deaths and potential touchpoints for intervention and prevention. NVDRS data has been used at the national and state level to monitor the magnitude of and trends in suicide and violence-related deaths, identify groups and communities experiencing a higher burden of such deaths, and enhance prevention approaches (e.g., Lyons et al., 2019; Stone et al., 2022; Wilson et al., 2023; see https://www.cdc.gov/nvdrs/stories/). For example, following a report showing a surge in suicides among 10–17-year-olds in Utah using NVDRS data, a state-wide youth suicide task force was launched and identified opportunities for expanded implementation of youth suicide prevention programs, including a mobile crisis intervention application, mobile crisis outreach teams, and firearm safety education resources (Ramseth, 2018).

Several publicly available databases compile information specifically on targeted violence and terrorism, with some data sources tracking incidents since the 1960s (Eyerman et al., 2021; LaFree & Gill, 2024). However, there remain several notable gaps in the available data that may limit their utility for public health prevention research and evaluation (Barth et al., 2019; Frederique, 2020; LaFree & Gill, 2024). Most notably, there is a distinct absence of a shared operational definition of targeted violence; subsequently, data collection and case inclusion criteria vary across sources (Sheehan, 2012). Currently available data sources tend to focus on forms of violence that overlap with, but are not limited to or inclusive measures of, targeted violence, such as school shootings and multiple-victim incidents (e.g., The Violence Project,¹⁴ K-12 School Shooting Database,¹⁵ Mass Attacks in Public Spaces,¹⁶ American School Shooting Study; National Institute of Justice, 2022); only capture explicit perpetrator intent to intimidate or further an agenda (e.g., Profiles of Individual Radicalization in the United States,¹⁷ Uppsala Conflict Data Program¹⁸); or exist to complement existing law enforcement data (e.g., National Incident-Based Reporting System).¹⁹ As databases do not align in the definitions and types of targeted violent incidents they collect, research based on different databases cannot easily be compared and findings may differ. Additionally, the use of multiple databases to estimate the scope of the problem or conduct etiological research is unreliable, as it cannot easily be determined which incidents, victims, or perpetrators are duplicated or unique to a database. Existing targeted violence databases are also limited by the sources from which information on incidents are obtained. First, databases do not all rely on the same set of sources for their data, which can impact the number of events included (Sheehan, 2012). Additionally, these databases often rely on journalists, media, and/or voluntary reports by law enforcement and criminal justice agencies (LaFree & Gill, 2024; Sheehan, 2012; E. Smith, 2021). As such, there is potential for bias toward capturing the types of incidents reported on and framed as targeted violence, affecting the number and types of incidents that make it into targeted violence databases. For instance, it is well-understood that, while mass shooting incidents and terrorist attacks tend to be high profile and captured reliably by related data systems, single-victim incidents of targeted violence are significantly underreported and underestimated (Pezzella et al., 2019; Sill & Haskins, 2023). Similarly, nonfatal incidents may not be considered worthy of media coverage or criminal investigation. Inconsistencies in what forms of targeted violence receive coverage, attention, and collection into databases can result in a lack of representativeness and biased research findings. Given the already low base rates of these incidents, unreliable measurement may further reduce the usefulness of these data sources for understanding patterns in the incidence of targeted violence and conducting etiological research.

Another limitation of existing data sources is that few currently collect information on the motivation and circumstances surrounding incidents, though there are efforts in progress to address this gap. For example, in 2023, DHS funded the Terrorism and Targeted Violence in the U.S. (T2V) project to create a robust, comprehensive data set based on open-source, event-level data to examine patterns of targeted violence in the United States (Miller & Jensen, n.d.). The planned data collection will include details about the locations, perpetrators, targets, tactics, weapons used, and casualties/outcomes for each terrorism and targeted violence attack. T2V data will be used to assess patterns and characteristics of mobilization to violence to inform intervention programming. This includes analysis of the grievances expressed by perpetrators to inform prevention approaches, as well as empirical assessments of the nature and evolution of preparatory behaviors that individuals engage in prior to committing violent attacks to identify optimal intervention points and support intervention-based community programs. There is potential for T2V to address gaps in existing open-source databases by collecting information on not only a broader range of targeted violence incidents but also a comprehensive set of variables that may be used to explore risk factors for perpetration.

As efforts to define and monitor the problem of targeted violence continue to evolve, there may be opportunities to leverage lessons learned from decades of public health violence surveillance to expand data collection and etiological research on targeted violence. Critically, developing and applying a uniform definition of targeted violence across different systems could make it possible to compare trends and prevalence across data sources and better understand the scope and scale of the problem. The public health field has successfully developed uniform definitions for multiple forms of violence to use in data collection systems and research (e.g., Basile et al., 2014; Gladden et al., 2014). For instance, CDC led the development of a uniform definition of intimate partner violence for use across organizations conducting surveillance on the issue; the conceptual and operational definitions not only supported consistency across measurement and data collection efforts but also allowed for intimate partner violence to be discussed across sectors (e.g., policy, research, advocacy) using a shared definition (Breiding et al., 2015). The targeted violence field could also look to established public health violence surveillance systems, such as NVDRS, to complement both existing law enforcement databases (e.g., National Incident-Based Reporting System) and open-source, event-level databases (e.g., Global Terrorism Database) currently collecting data on targeted violence. NVDRS already collects data on incidents of fatal violence, including whether a violent death was the result of a hate crime or terrorism. However, these types of incidents—particularly hate crimes—tend to be underreported to law enforcement and may not be recognized and labeled as hate crimes by law enforcement in reports to state and federal entities (Barth et al., 2019), likely resulting in underdocumentation within NVDRS. Despite these known challenges with underreporting, the system is nationally implemented, well-established, and has previously and continuously been used to monitor the incidence of violence. Expanding or improving the collection of the targeted violence variables in an existing system could advance public health data on these outcomes, requiring fewer resources than developing a new system. The use of a comprehensive public health surveillance system could increase the available evidence within the targeted violence field on the nature, scope, and circumstances of targeted violence to inform prevention efforts.

Identify Risk and Protective Factors for Perpetration

Identifying characteristics of the individual and their social and structural environment that increase or decrease the likelihood of perpetrating violence—called risk and protective factors—is a critical second step in the public health model for violence prevention. Effective primary prevention approaches for violence perpetration tend to operate by preventing or disrupting the development of risk factors, reducing or eliminating the influence of existing risk factors on behavior, and/or promoting the development of protective factors that can buffer individuals and communities against those risks. Thus, understanding what those factors are, how and when they develop, and which groups are most affected is critical to the development of effective prevention approaches.²⁰

Substantial progress has been made in the identification of risk and protective factors for violence and suicide over the last 30 years (Gerino et al., 2018; Schmidt et al., 2019; Tharp et al., 2013; Vagi et al., 2013). While some of these factors are specific to one type of violence, research has found that many are shared across violence types. Identification of shared risk and protective factors can inform the development of cross-cutting interventions to address multiple forms of violence and may help identify effective prevention strategies for one violence type that also prevent other forms of violence (DeGue et al., 2013). A 2014 CDC report (“Connecting the Dots”; Wilkins et al., 2014) reviewed research on risk and protective factors for seven types of violence (i.e., child maltreatment, teen dating violence, intimate partner violence, sexual violence, youth violence, bullying, and elder maltreatment) as well as suicide and identified 31 factors with evidence of association with multiple forms of violence perpetration and suicide (see Table 1). Many of these factors were associated with all, or nearly all, of the violence/suicide types reviewed, including a history of violence victimization, substance use, lack of problem-solving skills, social isolation, poor parent–child relationships, and witnessing violence. Although research on protective factors is more limited, strong connections with family, caring adults, school, and community supports were also consistently associated with lower risk for violence perpetration and suicide across types.

Table 1.

Shared Risk and Protective Factors for Targeted Violence and Other Violence Types and Suicide Included in CDC’s Connecting the Dots

Socioecological level	Shared risk and protective factors for violence perpetration	Targeted violence evidence (Review No. 1–6)
Risk factors
Individual	Low educational achievement	1–4a, 5a,b
	Poor behavioral control/impulsiveness	1, 4, 5b
	History of violent victimization	1, 2, 4, 6
	Psychological/mental health problems	1, 2c, 4c
	Witnessing violence	6d
	Substance use	4
Relationship	Social isolation/Lack of social support	1–3
	Poor parent–child relationships	1, 3, 6
	Family conflict	2, 6
	Economic stress (related to employment)	1, 2, 5b, 6e
	Associating with delinquent peers	1–3
Community	Diminished economic opportunities/high unemployment rates	4
Societal	Media violence	1, 3
	Societal income inequity	4
Protective factors
Relationship	Family support/connectedness	1, 3, 5, 6
	Connection to a caring adult	1, 6
	Association with prosocial peers	1, 2, 5
	Connection/commitment to school	1, 5
Community	Community support/connectedness	1, 3, 5

Note. CDC’s Connecting the Dots report (Wilkins et al., 2014) identified shared risk and protective factors across eight types of violence perpetration/suicide: child maltreatment, teen dating violence, intimate partner violence, sexual violence, youth violence, bullying, suicide, and elder maltreatment. Included factors have evidence for three or more forms of violence in addition to targeted violence. Systematic reviews of risk and protective factors for targeted violence outcomes were reviewed; those reviews that found support for one of the factors identified in Connecting the Dots are identified by number (1–6) as such: 1 = Wolfowicz et al. (2021); 2 = A. G. Smith (2018); 3 = Emmelkamp et al. (2020); 4 = Vergani et al. (2020); 5 = Lösel et al. (2018); 6 = Zych and Nasaescu (2022). CDC = Centers for Disease Control and Prevention.

^aHigher education is associated with some forms of targeted violence; lower education with other forms.

^bMeasured as a protective factor (e.g., low impulsivity).

^cMostly evident for “lone-wolf actors” (i.e., inspired by extremist ideologies but acting alone).

^dMeasured as witnessing violence between parents.

^eRelated to parental unemployment or poverty.

Likewise, a growing literature has identified a range of risk and protective factors associated with radicalization and specific forms of targeted violence behaviors (e.g., lone-actor, school shootings, terrorism, and hate-motivated targeted violence; Böckler et al., 2014; Cramer et al., 2020; Ebbrecht, 2023; Emmelkamp et al., 2020; Kenyon et al., 2023; Lösel et al., 2018; Zych & Nasaescu, 2022). In the most comprehensive systematic review to date,²¹ Wolfowicz et al. (2021) synthesized the evidence for more than 100 risk and protective factors for cognitive and behavioral radicalization and found that many factors examined in the targeted violence literature reflect the unique characteristics and theoretical foundations of this field. Measures of radical attitudes, identity fusion (i.e., a visceral sense of oneness with the group), dehumanization, radical peers or family, commitment to a cause, and authoritarian, antidemocratic, fundamentalist, or segregationist beliefs, for example, are particularly relevant to research examining the development of violent extremism—but are notably less useful for understanding other forms of violence. However, other risk and protective factors for targeted violence are likely not unique to these behaviors and, in fact, may overlap with those identified for other violence types. Identifying these shared risk and protective factors can build our understanding of the root causes of violence and advance efforts to identify effective prevention strategies that address targeted violence by drawing on the existing evidence for related violence types.

To provide an initial look at this overlap, we compared the shared risk and protective factors identified by CDC across suicide and seven forms of violence (Wilkins et al., 2014) with targeted violence risk and protective factors identified in six recent systematic reviews,²² each examining radicalization-related outcomes (that is, violent radicalization in juveniles, Emmelkamp et al., 2020; extremism and violent radicalization, Lösel et al., 2018; radicalization to terrorism, A. G. Smith, 2018; radicalization to violent extremism, Vergani et al., 2020; cognitive and behavioral radicalization, Wolfowicz et al., 2021; and family factors related to radicalization . Although radicalization is not a direct or comprehensive measure of targeted violence perpetration (i.e., not all targeted violence is preceded by radicalization and not all radicalization results in violent behavior), it may serve as a viable proxy for these low base-rate behaviors (Wolfowicz et al., 2021).

Table 1 lists the shared risk and protective factors for violence and suicide identified by CDC, organized by level of the social ecology and noting consistency within the outcomes reviewed. In addition, factors also supported by evidence from the targeted violence literature are identified. Of the 31 factors reviewed, 20 (64.5%) were also supported for targeted violence-related outcomes in at least one recent systematic review, including 15 risk factors and five protective factors. As with the broader violence literature, these shared factors were primarily (16 of 20) at the individual and relationship levels of the social ecology. Six categories of shared factors were identified: psychological (impulsivity, mental health problems, substance use), family (family conflict, poor parent–child relationships, family support/connectedness), peers (association with delinquent peers, association with prosocial peers), violence exposure (violence victimization, witnessing violence, media violence), social connectedness (social isolation/lack of social support, connection to caring adult, connection/commitment to school, community support/connectedness), and socioeconomic factors (low educational achievement, economic stress, diminished economic opportunities/high unemployment rates, societal income inequity). These categories suggest opportunities for early intervention and as well as approaches that address the social and economic conditions that increase risk. Many of these factors are common in the general population and may not reliably predict violence by an individual (i.e., risk assessment). However, their prevalence in the population impacts the likelihood that individuals will be exposed to the confluence of factors—both shared and unique to targeted violence—that might increase their vulnerability to radicalization and potential for violent behavior in the absence of protective factors. Thus, efforts to reduce exposure to cross-cutting risk factors and promote protective factors at the population level may reduce rates of both targeted violence, and other forms of violence that share those factors. This is a limited review of the literature and the factors identified herein may not be comprehensive. Many more shared risk and protective factors likely exist but did not appear in the preliminary evidence crosswalk provided here or have not been studied sufficiently across the general violence and targeted violence literature. However, these categories can provide some initial options for identifying promising prevention approaches for targeted violence from the broader violence prevention field while that evidence base is further developed.

Develop and Test Prevention Strategies

Informed by data on the burden and scope of the problem and evidence of risk and protective factors, the third step in the public health model involves developing and testing prevention strategies that operate on those factors in the populations at greatest risk. Evaluation research—particularly using rigorous experimental or quasi-experimental methods—can identify prevention approaches that “work” to prevent or reduce violent behavior. This evidence provides governments, communities, and other decision makers with critical knowledge to inform their prevention investments with greater confidence in the potential returns.

Evidence of what works to prevent violence has grown substantially over the last two decades (e.g., Kovalenko et al., 2022). Effective prevention approaches range from school or community-based programs to state or federal policies. To help communities put this growing scientific evidence base into action, CDC has released a series of Resources for Action²³ that distill the best available research evidence for preventing violence and suicide into a set of high-level strategies and specific evidence-based approaches (i.e., programs, policies, and practices) to advance those strategies. For example, the Sexual Violence Prevention Resource for Action identified “creating protective environments” as one of five key strategies that could be advanced through approaches focused on improving safety and monitoring in schools, establishing and consistently applying workplace policies, and addressing community-level risks through environmental approaches (Basile et al., 2016). Because different forms of violence are often influenced by the same risk and protective factors, many prevention approaches have demonstrated effects on multiple violence outcomes—pointing to the potential for well-designed prevention approaches to have cross-cutting impacts. For example, strategies focused on strengthening economic support for individuals, families, and communities are included in all six of the Prevention Resources for Action with evidence for a range of potential benefits, including reducing stress, enhancing stability, improving health, and preventing multiple types of violence (CDC, n.d.-b). Given some initial evidence of overlap in risk and protective factors for other forms of violence and targeted violence-related outcomes, it may be that these evidence-based strategies also have the potential for informing the development or identification of promising approaches to prevent targeted violence.

Attention to the primary prevention of targeted violence has expanded in recent years, resulting in the development and implementation of new approaches. As noted, the launch of CP3 at DHS represented a shift in federal prevention-related programs and efforts. These shifts included the expansion of a grant program supporting local prevention efforts, the placement of regional prevention coordinators around the country to build partnerships and facilitate program development, and the adoption of a public health-informed approach that emphasizes holistic, proactive, multidisciplinary, and evidence-based actions. Through their grant program, CP3 supports the implementation of “promising practices” for targeted violence prevention, including approaches focused on civic engagement, building youth resilience, training and awareness campaigns, bystander training programs, and programs that build skills to recognize and develop resilience to content that may spur violence (DHS, 2024c). Across the field, there has been an increase in the development and implementation of such prevention approaches for targeted violence. Wolfowicz et al. (2022) reviewed 64 counter-radicalization interventions from 13 countries and found that they most often addressed risk and protective factors in the domains of community resilience, social cohesion, and integration; attitudes toward others; norms and values; and personal skills. Based on the strength of evidence for the risk and protective factors addressed, Wolfowicz et al. (2022) suggest that approaches addressing attitudes toward others and personal skills may be most promising, and particularly those focused on increasing tolerance. At the same time, attention to factors like “machoism” (i.e., exaggerated masculinity and misogyny) and authoritarianism/fundamentalism are largely absent in existing strategies, despite the strength of the evidence for their role in radicalization (Wolfowicz et al., 2022).

Despite progress toward the development and implementation of primary prevention approaches in the field, effectiveness evaluations of these approaches remain very limited (Baruch et al., 2018; Bressan et al., 2024; Brouillette-Alarie et al., 2022; Gielen, 2019; Hassan et al., 2021; Jugl et al., 2021; Pistone et al., 2019; Wolfowicz et al., 2022). A recent meta-analysis found only nine “more or less well-controlled” outcome evaluations on extremism prevention from seven countries, including mostly quasi-experimental pre–post studies, one randomized controlled trial, and only one study from the United States (Jugl et al., 2021, p. 1). The meta-analysis found significant positive effects across outcomes related to extremism, pointing to the potential to demonstrate the effects of targeted violence prevention approaches with stronger evaluation designs. However, most studies assessed only psychological and attitudinal outcomes rather than violent behavior (Jugl et al., 2021). Similarly, a recent survey of 14 countries found that most evaluations of prevention approaches for violent extremism used qualitative or nonrigorous program evaluation methods (Bressan et al., 2024). Program evaluation research examining implementation quality, acceptability, and potential barriers to sustainability is critical to the program development process and to achieving community buy-in. Qualitative data—for example, interviews with participants or community leaders—can also provide critical data for program improvement and help us understand why a prevention approach may be working (or not; Bressan et al., 2024). Substantial investments in program evaluation have been made by DHS in the United States as well as globally to better understand program implementation and effects, and this critically important work continues to expand and improve (e.g., Bressan et al., 2024; DHS, 2023). In addition to program evaluation work, the need for more rigorous outcome evaluation in the field of targeted violence continues to be a critical gap inhibiting decision making by communities and policymakers on how best to invest in prevention resources. However, this work faces a variety of practical and methodological challenges, including the identification of appropriate outcome measures and the low incidence of cases which makes it difficult to determine statistically significant effects and establish control groups (DeMichele et al., 2023; Pistone et al., 2019).

Although a solid foundation exists, expansion of the evidence base for the primary prevention of targeted violence is critical to ensuring that investments to address this urgent public health and safety concern are both effective and aligned with the needs and capacities of communities. One approach to jump-starting the evidence base in this field involves building on the existing evidence for other forms of violence. Given that prevention approaches addressing shared risk and protective factors between violence types—or with other health outcomes—can have cross-cutting effectiveness, evaluating some of these approaches on targeted violence outcomes may also demonstrate promise for preventing these unique but related behaviors.

To help identify strategies with potential application to targeted violence, we reviewed CDC’s Resources for Action across five violence types and suicide and identified six evidence-based strategies (see Table 2) that address one or more shared risk or protective factors between targeted violence and other forms of violence or suicide and with potential to address the unique factors and contexts associated with targeted violence as well. These strategies include teaching skills to support emotional health and healthy relationships; promoting social norms that protect against violence; strengthening the economic security of individuals and families; promoting healthy connections in schools and communities; creating protective physical and social environments; and intervening to lessen the harms of violence and prevent future risk.

Table 2.

Examples of Potential Strategies and Approaches to Reduce Risk for Targeted Violence Based on the Best Available Evidence for Preventing Other Forms of Violence and Suicide

Strategy	Evidence-based approaches for violence and suicide prevention
Teach skills to support emotional health and healthy relationshipsa–f	Support resilience through education programs Healthy relationship skills programs Parenting skills and family relationship programs
Promote social norms that protect against violencea,c,f	Engaging men and boys to support healthy masculine norms Promote healthy peer norms Empower bystanders to challenge violence-supportive norms and behaviors
Strengthen economic security of individuals and familiesa,b,d–f	Job training and employment programs Social insurance programs Tax credits
Promote healthy connections in schools and communitiesd–f	Mentoring programs After-school programs Engage community members in shared activities Improve school climate and connectedness
Create protective physical and social environmentsb–e	Improve safety and monitoring in schools Reduce access to lethal means among persons at risk for suicide Modify the physical and social community environment Improve access to mental health and substance abuse services
Intervene to lessen harms and prevent future risk of violence/suicidea–f	Treatment to lessen the harms of violence exposure Treatment to prevent problem behavior and further involvement in violence Crisis intervention Community-justice partnerships

Note. Strategies and approaches identified address shared risk and protective factors for targeted violence and other forms violence and suicide in the following CDC Prevention Resources for Action. CDC = Centers for Disease Control and Prevention.

^aChild abuse and neglect (Fortson et al., 2016).

^bIntimate partner violence (Niolon et al., 2017).

^cSexual violence (Basile et al., 2016).

^dSuicide (CDC, 2022).

^eCommunity violence (CDC, 2024).

^fAdverse childhood experiences (CDC, 2019a).

Based on the Prevention Resources for Action, we identified a set of evidence-based prevention approaches (i.e., programs, policies, or practices) that may advance each strategy with the potential for preventing targeted violence outcomes. Each of these approaches is supported by research showing that it can reduce the risk for violence or suicide, as outlined in the Prevention Resources for Action (see Footnote 22). However, to our knowledge, none have yet been rigorously evaluated to examine potential effects on targeted violence. For example, a strategy focused on strengthening the economic security of individuals and families could address the impact of unemployment and financial stress on risk for targeted violence and radicalization through programs and policies that provide job training or employment assistance, unemployment insurance, or tax credits to stabilize household incomes and support low-income families (Brodeur & Yousaf, 2019; Wolfowicz et al., 2021). Similarly, a strategy that works to promote healthy, positive connections between individuals and their community may counteract the well-established role of social isolation in radicalization (Wolfowicz et al., 2021) and bolster the protective effects of prosocial, supportive relationships and connections to the community by connecting youth to positive adults, engaging community members in shared activities, and improving school climate. Although the evaluation of any prevention approach on targeted violence outcomes may pose several challenges (e.g., low base-rate behavioral outcomes, measurement; Baruch et al., 2018; Lopez et al., 2024), the strategies and approaches identified here may serve as an evidence-informed starting place for that work, allowing a more rapid advancement in the evidence base and practice.

Assure Widespread Adoption

Once effective prevention strategies have been identified, efforts to encourage widespread adoption and implementation are necessary to create population-level change. However, knowing what works is not enough to ensure uptake in communities. There are numerous challenges involved in bringing evidence-based prevention strategies to scale in “real-world” settings where resources, capacity, and other key supports are often more limited than in the research context where they were evaluated (Bumbarger et al., 2012). The field of implementation science seeks to systematically increase the uptake of evidence-based practices by identifying and addressing barriers to the adoption and implementation of evidence-based approaches, as well as facilitators that increase uptake and implementation quality across communities (Bauer & Kirchner, 2020). For example, research has shown that improving training, providing technical assistance, and addressing the resource needs of communities can encourage the uptake of evidence-based approaches as well as improve implementation quality and sustainability (Bumbarger et al., 2012). Further, developing or strengthening a multisectoral prevention infrastructure ensures communities can access well-trained staff, funding, critical partnerships, support networks, and populations to implement effective preventative programs, policies, and practices (Shapiro et al., 2015; Wandersman et al., 2008).

In the field of violence prevention, implementation research remains limited relative to the scope and depth of the evidence base for etiologic and evaluation research—though it is growing, including through research supported by CDC (e.g., Matjasko et al., 2022). The Division of Violence Prevention’s 2020–2024 strategic priorities included a focus on increasing the number of people exposed to effective violence prevention approaches by collaborating with funded communities and other partners to disseminate, implement, and scale-up proven strategies (CDC, n.d.-a). These efforts have largely focused on three areas, aligned with the Interactive Systems Framework for dissemination and implementation (Flaspohler et al., 2012; Wandersman et al., 2008): (a) synthesizing and translating the evidence into user-friendly formats for practitioners and communities; (b) providing tools, training, and technical assistance to support implementers; and (c) developing and building capacity for a prevention infrastructure that can implement evidence-based innovations to communities. For example, Violence Prevention in Practice²⁴ is an online resource that both translates evidence on effective prevention strategies and supports high-quality implementation across violence types by guiding practitioners through the selection, adaptation, implementation, and evaluation of strategies from CDC’s Prevention Resources for Action (Barranco et al., 2022). This resource is one of many tools and training included on VetoViolence,²⁵ a website developed by CDC to build the capacity of violence prevention practitioners and partners in the adoption and delivery of evidence-based strategies. CDC also developed the Violence Prevention Technical Assistance Center²⁶ to provide coordinated training and technical assistance to organizations receiving CDC funding for violence prevention work in communities, ensuring access to data-driven guidance to support effective implementation. In addition, the Rape Prevention and Education program, established by the 1994 Violence Against Women Act, has served to coordinate and expand the prevention infrastructure for sexual violence prevention in the United States since 2001 (DeGue et al., 2012). Rape Prevention and Education supports state and local health departments, sexual assault coalitions, rape crisis centers, and other community-based organizations, creating a national network of prevention practitioners and organizations. Over the last 25 years, Rape Prevention and Education funding has shifted from a focus on survivor support, community education, and awareness to the implementation of multilevel, evidence-based primary prevention approaches, exemplifying the impact of an evidence-informed, well-supported prevention infrastructure toward increasing widespread adoption of evidence-based prevention (DeGue et al., 2012).

In the field of targeted violence, DHS is similarly building community capacity for evidence-based primary prevention through several initiatives. For example, DHS Science and Technology Directorate²⁷—the research and evaluation arm of DHS—is working with academic researchers and practitioners to synthesize and translate research findings into actionable information, including research funded through the National Counterterrorism Innovation, Technology and Education²⁸ Center of Excellence. Science and Technology Directorate has also established the International Academic Partnerships for Science and Security to serve as a global knowledge hub bringing together academia, government, and industry to synthesize and advance the field of targeted violence and terrorism prevention.²⁹ To put this evidence into action, DHS CP3 has implemented nationwide regional prevention coordinators. These co-ordinators bring together state and local partners and prevention providers—including those focused on other forms of violence—to increase awareness of targeted violence and available prevention resources, provide training and technical assistance, advise on prevention strategy development and implementation, and improve information sharing between partners (DHS, 2024a). CP3 also supports the Prevention Practitioners Network,³⁰ which provides training and resources to more than 1,200 professionals engaged in targeted violence prevention efforts (e.g., community education and awareness, program implementation), as well as a referral network of mental health professionals trained to assess and intervene with individuals who may be at risk for engaging in targeted violence. The Prevention Resource Finder³¹ is a growing resource developed by CP3 in partnership with other federal agencies that provides access to a comprehensive up-to-date catalog of community support resources, grant opportunities, information-sharing platforms, federally funded research and reports, and training opportunities for a community of practice. The Prevention Resource Finder includes links to CDC’s violence prevention research, resources, and tools, increasing their reach among targeted violence practitioners. Together, these efforts by the federal government, alongside those implemented by non-governmental organizations, are building a prevention infrastructure capable of scaling up effective primary prevention strategies for targeted violence as the evidence base develops.

As we learn more about what works to prevent targeted violence, identify the factors that support the uptake and quality implementation of those innovations across contexts, and build the prevention infrastructure necessary to bring those approaches to communities, we are moving the science of violence prevention into action. This is a long-term process—and it is iterative and ongoing. New research builds on the existing evidence to improve understanding of the problem and inform the development of new, effective prevention approaches to be translated and disseminated. At the same time, prevention practitioners and communities carrying out violence prevention initiatives are also learning what works for them and what does not, as well as where the greatest needs, barriers, and strengths exist in the populations they serve. This practice-based evidence should then cycle back through the public health model to inform public health surveillance, etiologic research, prevention development, rigorous outcome evaluation, and implementation research to continually improve the quality and reach of approaches being applied in the field.

Toward a Research Agenda for the Primary Prevention of Targeted Violence

Substantial research literature exists examining the nature, causes, and circumstances of various forms of targeted violence, with an emphasis on terrorism, processes of radicalization and mobilization, psychological and behavioral risk factors and patterns, and the ideologies or motivations that define subtypes (Haghani et al., 2022; McBride et al., 2022). However, relative to the breadth of evidence in these areas, research on the primary prevention of targeted violence is still emerging and notably limited. Continued expansion of this evidence base is critical to ensuring that efforts to address this urgent threat to public health and national security are both effective and aligned with the needs and capacity of communities. There is no shortcut to developing, evaluating, and scaling up primary prevention approaches that “work”; the evidence base described here for other forms of violence has developed over several decades and continues to expand. But, as we sought to outline here, the broader fields of public health, violence prevention, and prevention science may offer researchers and policymakers both a framework for conceptualizing a research agenda on the primary prevention of targeted violence and some stepping stones to advance it more quickly.

Key Research Gaps and Opportunities

Aligned with the public health model, we suggest three key areas of research that may help move the targeted violence field toward a robust evidence base on primary prevention: measurement, modifiable risk and protective factors, and rigorous effectiveness evaluation of promising approaches.

Measurement

The measurement of targeted violence and related constructs for research purposes has been impeded by several challenges, including difficulties in establishing uniform definitions in the field, challenges with reliable and consistent information sources, relatively low incidence of targeted violence behaviors, and limitations of the etiological evidence base in identifying potentially causal pathways to targeted violence (Baruch et al., 2018; Gill, 2015; LaFree & Gill, 2024; Silke et al., 2023). While open-source, event-based databases have proven useful for examining the nature and circumstances of targeted violence cases and subtypes (LaFree & Gill, 2024), they have more limited utility for conducting etiological research (e.g., retrospective, no nonoffender comparison population, data source limitations) and are not sensitive enough for use in most prevention effectiveness research. In the absence of viable behavioral measures (i.e., attempted or actual violence perpetration) for those purposes, validated proxy measures (e.g., hate- or violence-supportive attitudes, cognitive radicalization, intentional exposure to extremist content) are needed to serve as indicators of perpetration risk. While more measurement development and validation work is likely needed, some useful proxy or indicator measures may already exist in the targeted violence field, as well as in violence research more broadly. Identifying potential measures already available for use by researchers and program evaluators would be helpful, particularly for researchers from other fields interested in assessing targeted violence in their work.

Modifiable Risk and Protective Factors

A recent, comprehensive DHS-funded systematic review by (Wolfowicz et al., 2020a, 2021) identified evidence for over 100 different risk and protective factors for cognitive and behavioral radicalization, highlighting the breadth of the etiological evidence base for, at least some, targeted violence-related outcomes. As discussed above, several of these factors align with those identified for other forms of violence or suicide, suggesting potential focus areas for developing, identifying, or adapting promising prevention approaches. However, the current evidence has some important gaps when it comes to informing the primary prevention of targeted violence in the United States. First, much of the available evidence examines radicalization-related outcomes (e.g., radical attitudes, intentions, and behaviors; Wolfowicz et al., 2021) as indicators of violent extremism and terrorism risk, with less known about risk and protective factors for other forms of targeted violence that may not be preceded by radicalization (e.g., grievance-, publicity- or some hate-motivated violence). Second, many factors have been examined in non-U.S. contexts and may not be as applicable to targeted violence originating in the United States. While Wolfowicz et al. (2021) found that most factors examined in their review were supported across regions, there was some variability in effect estimates by country and ideology, suggesting that some factors may be more salient than others in the development of U.S.-based primary prevention approaches. Finally, more attention is needed to identify modifiable risk and protective factors that can be addressed with preventative interventions. Understanding factors that are static (e.g., demographics, personality traits) or historical (e.g., past exposures and behaviors) may be necessary for identifying and disrupting developmental pathways to violence and informing important population-level prevention efforts. However, most prevention efforts tend to focus on modifiable risk and protective factors which can be changed (decreased or increased) or prevented through the implementation of programs, policies, or practices in communities and organizations, such as attitudes and beliefs, skills, knowledge, access to resources, and safe and supportive social and physical environments. Greater attention to these modifiable factors may help the field develop, adapt, or identify effective primary prevention approaches more quickly.

Rigorous Effectiveness Evaluation of Promising Approaches

The need for outcome evaluation research to identify effective targeted violence prevention approaches has been well-documented but remains a key gap in the field (Bressan et al., 2024; Jugl et al., 2021; Wolfowicz et al., 2022). The field of prevention science has established standards of evidence that define the ideal criteria for identifying effective preventative interventions ready for widespread dissemination, including the use of rigorous evaluation designs with the potential to draw causal inferences on behavioral outcomes (e.g., randomized controlled trials; Flay et al., 2005; Gottfredson et al., 2015). The purpose of these standards is to provide direction to the field—with the bar set intentionally high—to encourage innovation and advancements in methodology over time and improve the effectiveness of prevention efforts in communities. Evaluating the impact of primary prevention approaches on community-level outcomes, such as changes in rates of risk and protective factors for targeted violence in the population, can help overcome challenges in observing change at the individual level on low base-rate behaviors. For example, data from CDC’s Behavioral Risk Factor Surveillance System³² (e.g., adverse childhood experiences, loneliness, employment and financial stability, perceived discrimination) could be used to evaluate changes in risk and protective factors related to state- or local-level preventative interventions, such as policy initiatives or state action plans, over time. Measures of other attitudinal or behavioral risk factors for targeted violence may also serve as useful outcome measures, in the absence of more direct behavioral outcome measures (Wolfowicz et al., 2022). However, beyond establishing measurement options, meaningful expansion of the evaluation evidence also relies on the ability to (a) develop and identify promising approaches with an empirically based theory of change to evaluate and (b) utilize the most rigorous possible research designs given the context, intervention type, target population, resource constraints, and other factors. Table 2 provides an evidence-informed starting place for identifying some promising approaches that have not yet been evaluated on targeted violence outcomes but have been rigorously evaluated on other violence and suicide outcomes. Adding measures of targeted violence-related risk and protective factors to ongoing evaluations of violence prevention approaches—such as those being evaluated through the CDC-funded Youth Violence Prevention Centers (D’Inverno & Bartholow, 2021)—may be a lower-cost way to pilot outcome measures, expand the evidence base, and gain knowledge that can inform future research investments. Many of the approaches being evaluated by the Youth Violence Prevention Centers, for example, align with the strategies identified here (Table 2) as having potential for preventing targeted violence. Alternative approaches to process and program evaluation, such as those suggested by Romaniuk and Fink (2012; e.g., conducting evaluability assessments before program implementation), can also “move the needle” on understanding the impact of preventative interventions and lay the groundwork for identifying promising approaches and conducting more rigorous effectiveness evaluation. However, conscious shifts in the field to develop and provide the necessary resources, innovations, and expertise to engage more fully in rigorous effectiveness evaluation research will be critical to ensuring that investments in primary prevention are reducing risk for targeted violence at the population level and protecting the country from this urgent threat to public health and safety.

Conclusion

Targeted violence is not only a threat to national security and public safety but also a public health problem that threatens the health, wellbeing, and safety of our communities. Applying CDC’s public health approach to violence prevention as well as lessons learned from decades of general violence prevention research can advance research and practice for the primary prevention of targeted violence in the United States. In addition to informing the work of targeted violence researchers and practitioners, there is an important opportunity to engage in this work with violence researchers with experience conducting etiological, evaluation, and implementation research on other forms of violence. Likewise, engaging the public health community and its role as a facilitator of partnerships across sectors, including academic, community service and health organizations, education, business, criminal justice, policymakers, faith-based organizations, and other partners may help expand the expertise and experience needed to address this problem (Cramer et al., 2020). Working together—across fields of research and practice, sectors, agencies, and communities—can accelerate evidence-based prevention efforts and reduce the threat of targeted violence in the United States.

Public Significance Statement.

Targeted violence is an urgent threat to national security and a preventable problem. A four-step public health approach has been applied for four decades by the Centers for Disease Control and Prevention and the public health field to develop and support evidence-based primary prevention approaches for other forms of violence (e.g., sexual violence, community violence, and intimate partner violence) and suicide. Building on this evidence base can advance the work of researchers and practitioners, complement the work of law enforcement and intelligence agencies, and facilitate partnerships across different community sectors to address and prevent targeted violence.