The present study focuses on the role of deviant peers, parent child-rearing practices, and parent alcohol use in the initiation of marijuana and alcohol use during adolescence. Composite measures of Deviant Peers and Parental Monitoring were used that incorporate both the parents′and child's report of these variables as well as the parents′report of their own alcohol use and the adolescent's report of marijuana and alcohol use. Multiple regression analyses incorporating Parental Monitoring, Mother Alcohol Use, and Deviant Peers as independent variables revealed significant standardized b coefficients for Deviant Peers predicting alcohol use, and both Parental Monitoring and Deviant Peers predicting marijuana use. A profile analysis showed that delinquent drug users had lower parental monitoring and more deviant peers than nondelinquent drug users or abstainers. However, a group of youngsters were identified who reported some substance use but were not antisocial; these youngsters resembled abstainers in respect to the degree that they were monitored by parents and exposed to deviant peers. Taking these results into consideration, along with longitudinal studies on adolescent delinquency and adult alcoholism, it is hypothesized that adolescent delinquency and drug use are outcomes of disrupted family processes and exposure to deviant peers, and that adolescents who are both antisocial and use drugs may be at higher risk for eventual substance abuse.