Background. This study assessed the relationship of early adolescent marijuana use to performance of developmental tasks integral to the transition to young adulthood. The tasks concerned intimacy, education, and work and social conformity.

Methods. African American (N = 617) and Puerto Rican (N = 531) youths completed questionnaires in their classrooms. Five years later they were individually interviewed. Logistic regression analysis estimated the increased likelihood that early marijuana users would make an inadequate transition to young adult social roles.

Results. Analyses examining the association between early marijuana use and 20 outcome variables found significant relationships for 10 of them: (a) having lower educational and occupational expectations; (b) being suspended or expelled from school, fired from jobs, ‘high’ at school or work, collecting welfare; and (c) rebelliousness, not participating in productive activities, not attending church, and being an unmarried parent. Marijuana use was not related to any of the intimate relationship measures. These finding emerged with controls on gender, ethnicity, age and mother's education.

Conclusions. Among African Americans and Puerto Ricans, early marijuana use predicts less adequate performance on some developmental tasks integral to becoming an independent young adult. Marijuana is not a benign drug and is associated with future risks for the individual and society at large.