AbstractIntroductionPrevious research has found that impulsivity and deviant peer affiliation predict alcohol use among adolescents. However, it remains unclear to what extent these risk factors predict alcohol use in conjunction with one another, and to what extent they predict over and above correlated risk factors, such as pre‐existing externalizing problems and sociodemographic characteristics. The present study tested the hypothesis that deviant peer affiliation would mediate the prospective association between impulsivity and alcohol use in adolescence (ages 13–18 years), controlling for a wide range of family and child‐level covariates.MethodsAnalyses were conducted using data from 2318 participants from the Longitudinal Cohort Study of the Project on Human Development in Chicago Neighborhoods. Participants were approximately 9, 12, or 15 years of age at wave 1 of the study, with waves 2 and 3 taking place at approximately 2‐year intervals. The sample composition was 50.3% male, 46.1% Hispanic, 35.6% Black, non‐Hispanic, 14.4% White, non‐Hispanic, and 3.9% other race/ethnicity.ResultsResults from path analyses indicated that the prospective association between impulsivity and alcohol use was mediated by peer deviance, but only for the oldest (age 15) cohort.ConclusionsFindings from the present study suggest that despite impulsivity being a dispositional characteristic, its effects on alcohol use in later adolescence are achieved through a social pathway, via affiliation with deviant peers. It further suggests that this pathway, especially the link from impulsivity to affiliation with deviant peers, may not operate until late adolescence. Findings suggest that alcohol use may be prevented or reduced among impulsive adolescents by reducing their exposure to delinquent peers.