This study applies multilevel social network analytic techniques to examine processes of homophilic selection and social influence related to alcohol use among friends in early adolescence. Participants included 3,041 Dutch youth (M age =12 years, 49% female) from 120 classrooms in 14 schools. Three waves with 3-month intervals of friendship nomination data and self-reports of drinking behavior were collected. Results revealed that within classrooms, friendship nominations tended to be reciprocated and dyadic friendships tended to be embedded within cohesive subgroups (e.g., cliques). Students tended to nominate friends who were the same sex, from a similar ethnic background, and who they previously knew from primary school. Selection processes turned out to play a more significant role than social influence processes in predicting similarity between early adolescent friends' alcohol use. Although friendship dynamics and individual drinking trajectories substantially differed between classrooms, the effects of homophilic selection and social influence did not.