... Individual factors such as prior delinquency (Esbensen 2000;Hill et al., 1999;Klein & Maxson, 2006), antisocial attitudes (e.g., negative views of the police, positive attitudes towards gangs and violence; Esbensen, 2000;Esbensen et al., 2009;Friedman, Mann, & Friedman, 1975;Hawkins et al., 2009), a history of aggressive behaviour (Dahlberg, 1998;Sanchez-Jankowski, 1991), a proclivity for excitement and trouble (Esbensen & Weerman, 2005), alcohol and drug use (e.g., Bjerregaard & Lizotte, 1995;Lizotte, Tesoriero, Thornberry, & Krohn, 1994), and non-delinquent problem behaviours (e.g., hyperactivity, reactivity, impulsivity, anger management problems) (Hill et al., 1999;Kosterman et al., 1996) increase the likelihood of youth gang involvement. Although research into gang involvement has been largely influenced by theories from criminology and sociology (Bennett & Holloway, 2004), psychological variables such as learning difficulties (Hill et al., 1999), high levels of anxiety, hyperactivity, mental health problems, history of suicide attempts (Dukes, Martinez, & Stein, 1997;Yoder, Whitbeck & Hoyt, 2003), low levels of empathy and remorse (Dupere et al., 2007), and the experience of traumatic or negative life events (e.g., Klein & Maxson, 2006) have been suggested to influence an inclination for gang membership. ...