Using a probability sample of 4,230 adolescents from grades 7-12, we used negative binomial regression to estimate the effects of peer and six family variables on the risk of adolescent drug use. Peer drug use had relatively strong effects of adolescent drug use. Parental drug attitudes, sibling drug use, and adult drug use had significant direct effects net of peer influences. In addition, they had significant indirect effects that were mediated by peer drug use. The influences of parental monitoring, attachment to mother, and attachment to father were statistically significant but relatively small. The findings applied to alcohol, binge drinking, cigarettes, marijuana, and other illicit drugs. Editors' Strategic Implications: The authors interpret their findings as being more consistent with social learning than social control theory. This research, although cross-sectional and limited to adolescents' self-reports, contributes to a growing literature on the direct and indirect influences of parents on their teens' substance use rates. It speaks to the need for school- and community-based prevention efforts to focus on families as well as peers.