Early conduct problems have been linked to early marijuana use in adolescence. The present study examines this association in a sample of 1,076 college students that was divided into three groups: (1) early marijuana users (began marijuana use prior to age 15; N = 126), (2) late marijuana users (began marijuana use at or after age 15; N = 607), and (3) nonusers (never used marijuana; N = 343). A conduct problem inventory used in previous studies was adapted for use in the present study. Early conduct problems were associated with early marijuana use but not with late marijuana use, holding constant other risk factors. Results suggest that early conduct problems are a risk factor for early marijuana use even among academically achieving college-bound students. (Contains 4 tables.)