Table 2. Measurement of distal and proximal factors.

Variable	Description
Gender	Gender of child was measured via mother's self-report at age 6.
Distal Factors
Child and adolescent behavior
Classroom behavior	Measured in first grade. Teacher reported using the Teacher Observation of Classroom Adaptation (TOCA) of any maladaptive classroom behavior in five behavioral domains: shyness (e.g. timid, alone too much, friendless), aggressiveness (e.g. fights, lies, resists authority, disobedient), underachievement (e.g. does not work as well as assessment of ability indicates), restlessness (fidgets, is unable to sit still in class), and immaturity (e.g. acts too young physically and/or emotionally, cries too much, seeks too much attention). The TOCA measure has been shown to be valid and reliable (Kellam, Branch, Agrawal, & Ensminger, 1975).
Delinquency	Measured in adolescence. The sum of 18, 4-point self-reported indicators. Range 0-72, α = 0.83. Items were adapted from a scale by Gold and colleagues (1970).
Early family environment
Family poverty	Measured in first grade and adolescence. Using poverty guidelines from the Office of Economic Opportunity for 1967 and 1976 (Department of Health, Education and Welfare, 1977), categories of no poverty, poverty at either childhood or adolescence, or persistent poverty (poverty in childhood and adolescence) created from primary caregiver's self-report of income and household size.
Parental education	Measured in first grade. Self-reported education level of primary caregiver: dichotomized into 0-11 years vs. 12+ years of education.
Family involvement	Measured in adolescence. Sum of five indicators (e.g., how often family members did things together such as work on homework and do community activities) ranging from 5=less than every few months to 1= several times a week. These were summed into a single construct. Range: 5-30; α=0.69.
Family conflict	Measured in adolescence. Sum of five indicators (e.g., how often family members said mean things to each other, how often family members yelled at each other) ranging from 5=less than every few months to 1= several times a week. These were summed into a single construct, Range: 5-30; α = 0.94.
Academic achievement
Readiness to learn	Measured in first grade. Metropolitan Readiness to Learn, a standardized test administered in schools in 1st grade as a measure of a child's readiness for school (Anastasi, 1968). Range 0 (i.e., not ready) to 100 (i.e., very ready).
School bonds	Measured in adolescence. Sum of five, 5 and 6 point self-report indicators (e.g., “how far do you think you will go in school?,” “how often do you skip school?”). Range: 5-28; α= 0.67.
Educational attainment	Measured at age 32. Dichotomized into obtained high school diploma vs. did not obtain high school diploma.
Early mental health
Childhood psychological wellbeing	Measured in first grade. Using the Mother Symptom Inventory (validity previously demonstrated; Conners, 1967), the mother (or primary care giver) self-reported a 4 point 38-item inventory of symptoms of depression and anxiety in children. Tertiles were created of low, moderate, high scores, α= 0.79.
Adolescent mental health	Measured in adolescence. A self-report of anxiety and depression symptoms: six depression questions and seven anxiety items. Response choices were on a scale of 1 to 6, ranging from “not at all” to “very, very much.” Each scale was standardized. Psychometric examination of these original measures is published elsewhere and shows a moderate degree of internal consistency for both depression (α=0.69) and anxiety (α=0.68) and construct validity is also demonstrated (Petersen & Kellam, 1977).
Help received in adolescence	Measured in adolescence. Mother's report of whether child received any help for emotional, learning, behavioral, or drug problems from a youth agency since childhood assessment. Dichotomized to any help vs. no help.
Adolescent substance use
Alcohol use	Measured in adolescence. Self-report of whether ever used and frequency of beer, wine, liquor. Categorized into no use, experimental use (1-19 times), and regular use (20+ times).
Early substance use	Measured in adolescence. Self-report of any substance use (marijuana, cocaine, LSD/psychedelics, amphetamines/uppers, barbiturates/downers, tranquilizers, opiates, inhalants, and cough syrup/codeine use) before age 14.
Adolescent-onset substance use disorder	Measured at age 32. The Composite International Diagnostic Interview (CIDI), a structured diagnostic interview developed by the University of Michigan for the National Comorbidity Survey (Kessler et al., 1994) was used to construct the age of onset of a substance use disorder. Responses were then categorized into adolescent-onset (≤18 years) vs. no adolescent-onset.
Proximal Factors
Substance use severity	Substance use disorder symptoms were measured at age 32. The number of substance use disorder symptoms endorsed on the CIDI was used as a continuous measure of substance use severity. (Range 0-11).
Socioeconomic status at age 32
Health insurance	Measured in young adulthood (age 32). Self-report of current receipt of any health insurance.
Poverty	Measured in young adulthood (age 32). Using 1992 Federal guidelines from the Department of Health and Human Services, individuals were dichotomized into below or above the poverty threshold based on self-reported income and household size.
Unemployment	Measured in young adulthood (age 32). Self-report of current unemployment.