Do peer influences have the same effect on religious and nonreligious youth, or does religiosity reduce the effect of peers on delinquency? Using data from the National Youth Survey, the authors examined the interaction of religiosity and peer influences on marijuana use, alcohol use, hitting, and property offenses. The results suggest that, for marijuana use and alcohol use, three measures of peer influencepeer attitudes, behaviors, and pressurehave weaker effects on religious adolescents. Thus, even when religious youth are exposed to peers who encourage substance use, religiosity may serve as a protective factor that reduces the effect of peers. In contrast, religiosity does not seem to condition the effect of peers on hitting and property offenses. (Published Abstract)