The purpose of this paper was to assess the relative effects of parents and peers on adolescent alcohol use via mechanisms of attachment and opportunity. Panel data from the second and third waves of the National Education Longitudinal Survey (NELS:88) were used to examine the relationship between multiple measures of peer and parent-child relations reflecting these concepts and alcohol use among high-school students. Overall, our results indicated that peers are more influential than parents in shaping adolescents’ patterns of alcohol consumption and that unstructured peer interaction is an especially powerful predictor of adolescent alcohol use and binge drinking. Our findings further suggest that gender serves as a conditioning factor, moderating the effects of parental and peer variables on high-school students’ drinking. Potential programmatic applications, as well as the theoretical implications, of these findings are discussed within the context of control theory and prior research on the relationship between opportunity and delinquency.