Overall, the findings indicated that college students who experienced multiple negative or stressful life events and socialized with substance using social groups were at increased risk for developing substance use problems. Specifically, the findings revealed that alcohol use problems among college students were associated with greater problematic drug use and regular use of illicit drugs in social groups. Drug use problems were associated with being male, having greater alcohol use problems, regular use of alcohol and drugs in social groups, illicit drug use among romantic partners, and higher numbers of negative or stressful life events. The findings suggest that college students may be using alcohol and drugs to cope with instability in their lives or may simply be modeling peer group behavior. Participants were 616 college students who were recruited from an introductory psychology course. Participants completed a series of questionnaires either via paper-and-pencil or via a Web-based version that assessed their substance use, peer substance use, life events, and personality features. Data analysis included the use of descriptive statistics and binary logistic regression models. The findings of this study underscore the need for more research on the environmental factors associated with alcohol and drug use problems on college campuses. Tables, references