Level of evidence and criteria	Resilience factors
Level 1: strong evidence (SRs and MAs) Factor has been studied for its association with resilience (i.e. mental health or well‐being or psychological adaptation despite (acute or chronic) stressors, life events or traumas) in observational (cross‐sectional or longitudinal) studies in adults There is evidence from systematic reviews (SRs) AND meta‐analyses (MAs)
Level 1a: there is evidence for this factor from several SRs AND several MAs (both across different populations)	Active coping (e.g. problem‐solving, planning) 2 MAs: Kvillemo 2014; Moskowitz 2009 4 SRs: Bjørkløf 2013; Kneebone 2003; Senra 2015; Van Kessel 2013 Cross‐sectional studies: e.g. Al‐Yagon 2009; Dörfel 2008; Lechner 2007; Luo 2015; Marty 2010; Wang 2014 Longitudinal studies: e.g. Butler 2009; Silver 2002 Self‐efficacy 2 MAs: Jackson 2014; Lee 2013 9 SRs: Allart 2013; Dias 2015; Korpershoek 2011; Luszczynska 2009; Morris 2013; Peter 2012; Stewart 2011; Van Kessel 2013; Van Leeuwen 2012 Cross‐sectional studies: e.g. Barry 2003; Northouse 2002; Orengo 2001; Schwarzer 2008; Wright 2008 Longitudinal studies: e.g. DeRoon‐Cassini 2010; Guest 2015; Hartley 2008 Optimism or positive attributional style 4 MAs: Helgeson 2006; Lee 2013; Prati 2009; Shand 2015 5 SRs: Dias 2015; Duits 1997; Peter 2012; Stewart 2011; Van Kessel 2013 Cross‐sectional studies: e.g. Martin‐Krumm 2003; Sumer 2005 Longitudinal studies: e.g. Ahmad 2010; Carver 2010; Fresco 2006; Grote 2007; Kivimäki 2005; Myhren 2010; Segovia 2012 Social support 4 MAs: Lee 2013; Ozer 2003; Prati 2009; Shand 2015 11 SRs: Allart 2013; Casale 2013; Dias 2015; Duits 1997; McCann 2013; Morris 2013; Paterson 2013; Pragodpol 2013; Senra 2015; Stewart 2011; Van Kessel 2013 Cross‐sectional studies: e.g. Ahern 2004; Fuller‐Iglesias 2008; Kaspersen 2003; Schumm 2006 Longitudinal studies: e.g. Bartone 1989; Dyrbye 2010; Johnson 2009; Koenen 2003; Solomon 1988 Cognitive flexibility (e.g. positive reappraisal, acceptance of negative situations and emotions)a 6 MAs: Helgeson 2006; Kvillemo 2014; McIntosh 2012; Moskowitz 2009; Prati 2009; Shand 2015 11 SRs: Allart 2013; Bjørkløf 2013; Dias 2015; Guardino 2014; Kneebone 2003; Morris 2013; Nowlan 2015; Peter 2012; Senra 2015; Stewart 2011; Van Leeuwen 2012 Cross‐sectional studies: e.g. Bailey 2013; Farber 2003; Johnson 2015; Min 2013 Longitudinal studies: e.g. Park 2008; Silver 2002; Wade 2001 Religiosity or spirituality or religious coping (e.g. frequent religious attendance)a 7 MAs: Ano 2005; Helgeson 2006; McIntosh 2012; Moskowitz 2009; Prati 2009; Salsman 2015; Shand 2015 7 SRs: Bjørkløf 2013; Guardino 2014; McCann 2013; Peter 2012; Senra 2015; Stewart 2011; Visser 2010 Cross‐sectional studies: e.g. Cruz 2016; Tsai 2015 Longitudinal studies: e.g. Hebert 2007; Kasen 2014; Koenig 2007; Walsh 2002
Level 1b: there is evidence for this factor from several SRs AND a single MA (both across different populations)	Positive emotions or positive affect 1 MA: Lee 2013 2 SRs: Van Kessel 2013; Van Leeuwen 2012 Cross‐sectional studies: e.g. Cohen 2006; Gloria 2016; Ong 2006 Longitudinal studies: e.g. Fredrickson 2003; Geschwind 2010; Quale 2010; Strand 2006; Zautra 2005 Hardiness 1 MA: Eschleman 2010 4 SRs: Brooks 2003; Dias 2015; McCann 2013; Stewart 2011 Cross‐sectional studies: e.g. Alexander 2001; Andrew 2008; Bernas 2000; Farber 2000; Hystad 2011; Judkins 2005a; King 1998; Natvik 2011; Waysman 2001; Weiss 2002 Longitudinal studies: e.g. Dolan 2006; Bartone 1989 Self‐esteem 1 MA: Lee 2013 4 SRs: Allart 2013; Peter 2012; Stewart 2011; Van Leeuwen 2012 Cross‐sectional studies: e.g. Besser 2014; Fernández‐Lansac 2012; Hayter 2014 Longitudinal studies: e.g. Bookwala 2014
Level 1c: there is evidence for this factor from several SRs (across different populations) AND a single MA (in the same population)	Meaning in life or purpose in life 1 MA: Winger 2016 5 SRs: Allart 2013; Peter 2012; Van Kessel 2013; Van Leeuwen 2012; Visser 2010) Cross‐sectional studies: e.g. Alim 2008; Bauer‐Wu 2005; Blackburn 2015; Feder 2013; Lyon 2001; Owens 2009; Pietrzak 2013; Schaefer 2013; Smith 2009; Tsai 2015 Longitudinal studies: e.g. Krause 2007; Tsai 2016 Sense of coherence 1 MA: Winger 2016 7 SRs: Allart 2013; Bjørkløf 2013; Eriksson 2006; Peter 2012; Pragodpol 2013; Van Kessel 2013; Van Leeuwen 2012) Cross‐sectional studies: e.g. Al‐Yagon 2009; Cohen 2003; Forstmeier 2009 Longitudinal studies: e.g. Frommberger 1999; Schnyder 2008
Level 2: moderate evidence (only SRs or single MA) Factor has been studied for its association with resilience (i.e. mental health or well‐being or psychological adaptation despite (acute or chronic) stressors, life events or traumas) in observational (cross‐sectional or longitudinal) studies in adults There is evidence from SR OR a single MA
Level 2a: there is evidence for this factor from several SRs (across different populations) OR there is no evidence from SRs, but from a MA (across different populations)	(Internal) Locus of control 6 SRs: Bjørkløf 2013; Dias 2015; Saksvik 2011; Senra 2015; Stewart 2011; Van Leeuwen 2012 Cross‐sectional studies: e.g. Kilic 2013; Sattler 2014; Solomon 1988 Longitudinal studies: e.g. Karstoft 2015; Lawler 1992; Milte 2015; White 2012a Coping flexibility 1 MA: Cheng 2014 Cross‐sectional studies: e.g. Atal 2016; Bonanno 2011; Burton 2012; Park 2015 Longitudinal studies: e.g. Bonanno 2004; Galatzer‐Levy 2012
Level 2b: there is evidence for this factor from several SRs (in the same population)	Hope 2 SRs: Peter 2012; Van Leeuwen 2012 Cross‐sectional studies: e.g. Besser 2014; Hernandez 2013; Ong 2006; Truitt 2012 Longitudinal studies: e.g. Ho 2010
Level 2c: there is evidence for this factor from a single SR (in the same population)	Humour 1 SR: McCann 2013 Cross‐sectional studies: e.g. Abel 2002a; Abel 2002b Longitudinal studies: e.g. Kuiper 1992; Nezu 1988
Level 3: weak evidence (no SR or MA) Expert opinion without explicit critical appraisal Factor has not been studied sufficiently for its association with resilience (i.e. mental health or well‐being or psychological adaptation despite (acute or chronic) stressors, life events or traumas) in adults Factor is only mentioned in unsystematic narrative reviews or discussion papers, or both
	Altruism Narrative reviews or discussion papers: Haglund 2007; Southwick 2005; Wu 2013
MA: Meta‐analysis; SR: Systematic review.