Research indicates that gender is one of the strongest correlates of juvenile delinquency. Additionally, a growing body of literature suggests that the association with delinquent peers is an important predictor of delinquent behavior. Although a few studies have examined how delinquent peers condition the gender-delinquency relationship, the authors extend this body of literature by using longitudinal data from a sample of adolescents to explore the extent to which internal and external constraints condition the relationship between gender, delinquent peers, and delinquent behavior. Findings indicate that delinquent peer association is an important predictor of delinquency generally, but the effect varies across gender. Specifically, delinquent peer associations are a better predictor of delinquency among boys compared to girls. In addition, the effect of delinquent peers on delinquency varies according to the level of internal and external constraints. Future research directions for unraveling the role of gender in youthful offending are discussed.