The goal of this study was to explore whether supportiveness from a parent or a friend moderated the effects of the supportive person's drinking on the trajectory of adolescent alcohol abuse dependence symptoms. High-risk adolescents recruited from shelters and a matched sample of adolescents recruited from the sheltered adolescent's former neighborhood completed assessments at baseline, 6, 12, and 18 months. Measures included the Social Network Interview, assessing the drinking and supportiveness of everyone in the network. The alcohol module of the Diagnostic Interview Schedule for Children was also administered. Hierarchical Linear Modeling identified predictors of the trajectory of alcohol symptoms of the 401 adolescents over 18 months. The results showed that the baseline levels of parental drinking predicted increased symptoms over time only for those with low parental support. In contrast, the baseline level of peer alcohol use predicted increased symptoms over time only for those with high peer support. The pattern of results did not differ for shelter youth compared to neighborhood controls.