--- - |2 The present research examines social influences on self‐reported frequency of drunkenness in a longitudinal sample of 1,439 adolescents (46% female, 90% White, mean age = 14 at baseline) with social network measures from friends, romantic partners, and romantic partners’ friends. We build on past research by addressing multiple mechanisms of social influence—peers’ frequency of drunkenness, alcohol‐related attitudes, and unstructured socializing—across relationship types. Adolescents’ drunkenness frequency increased when their friends’ and partners’ friends’ drunkenness frequency increased and when their romantic partners’ positive alcohol‐related attitudes increased. Furthermore, the association between unstructured socializing and frequency of drunkenness was stronger for older than younger adolescents. Results advance understanding of the social transmission of alcohol use in adolescence and inform intervention efforts. - Journal of Research on Adolescence, EarlyView.