This study addresses not only influence and selection of friends as sources of similarity in alcohol use, but also peer processes leading drinkers to be chosen as friends more often than non-drinkers, which increases the number of adolescents subject to their influence. Analyses apply a stochastic actor-based model to friendship networks assessed five times from 6th through 9th grades for 50 grade cohort networks in Iowa and Pennsylvania, which include 13,214 individuals. Results show definite influence and selection for similarity in alcohol use, as well as reciprocal influences between drinking and frequently being chosen as a friend. These findings suggest that adolescents view alcohol use as an attractive, high status activity and that friendships expose adolescents to opportunities for drinking.