College drinking occurs at a stage in life when drinking levels are generally elevated. Compared to all other age groups, the prevalence of periodic heavy or high-risk drinking is greatest among young adults aged 19 to 24; and among young adults, college students have the highest prevalence of high-risk drinking (Johnston et al., 2001b; Substance Abuse and Mental Health Services Administration, 2001). Although their noncollegiate peers drink more often, college students tend to drink more heavily when they do drink (O'Malley and Johnston, 2002).