the initiation (Hawkins et al. 1992) and escalation (Morojele and Brook, 2001) of substance use. Finally, personal experience using alcohol and tobacco predicts the initiation and escalation of marijuana and other illicit substance use (Bentler et al. 2002; Boyle et al. 1992; Clark et al. 1998, 2005; Ellickson et al. 2004b; Novins and Mitchell, 1998; van den Bree and Pickworth, 2005).
