Objective: Young adulthood (18-25) is the peak age for substance use, but friends who engage in positive behaviors may be protective. The present study examined the direct relation between positive peer affiliation and substance use, and whether positive peer affiliation moderated the relation between self-reported sensation-seeking, future orientation, self-regulation and substance use. Participants: Participants were 382 college students (M[subscript age] = 19.25, SD = 1.33). Method: Participants completed questionnaires assessing substance use, peer affiliation, sensation-seeking, future orientation, and self-regulation. Results: In structural equation models, positive peer affiliation was negatively associated with drunk driving, cigarette use, and marijuana use; and moderated relations between sensation-seeking and substance use, but not cognitive control in the predicted direction. Conclusions: Substance use remains a salient public health concern for college students, but the current study found that having friends who generally engage in positive activities is an important buffer against socioemotional risk factors.