From learning and opportunity perspectives, peer group structural dimensions shed light on social processes that can amplify or ameliorate the risk of having delinquent friends. Previous research has not accounted for a primary criminological variable, self-control, limiting theoretical clarity. The authors developed three hypotheses about self-control's potential role in deviant peer structure: it may underlie and explain the (spurious) relationship between deviant peers or peer structure and delinquency, be partially exogenous to deviant peers and deviant peer structure, and moderate the effects of deviant peers and deviant peer structure. To test these hypotheses, the authors used data from a longitudinal sample of adolescents containing peer self-reports of delinquency. The results suggest that self-control and deviant peers are complementary. This is the first study demonstrating this relationship with self-reports of deviance rather than perceptions. Less support was found for the conditioning impact of deviant network structure than in previous work. Some differential patterns also emerged by gender and race. Implications of these findings are discussed. (Contains 23 notes and 7 tables.)