The present study examines the role of communication in shaping norms and behaviors with significant personal and societal consequences. Based on primary socialization theory and the general theory of family communication, parental anti-substance-use socialization processes were hypothesized to influence early adolescents' substance use norms and behaviors. Using longitudinal data (N =1,059), the results revealed that parent-adolescent prevention communication about substance use in the media and parental anti-substance-use injunctive norms were positively associated with early adolescents' personal anti-substance-use norms, which, in turn, led to decreases in recent alcohol, cigarette, and marijuana use. It was also found that family expressiveness and structural traditionalism positively related to the hypothesized association between parental socialization processes and early adolescents' norms and behaviors.