The association between community-aggregated levels of individual and peer risk and protective factors and prevalence of adolescent substance use was examined in repeated cross-sectional data among youth in 41 communities ranging in population from 1,578 to 106,221. The association between community levels of these risk and protective factors in 2000 and substance use 2 years later was examined by using within-cohort analyses (e.g., sixth grade in 2000 predicting eighth grade in 2002) and cross-cohort analyses (e.g., sixth grade in 2000 predicting sixth grade in 2002). In both within-cohort and across-cohort analyses, community-aggregated levels of peer and individual risk and protective factors predicted adolescent substance use 2 years later, suggesting that focusing on elevated peer and individual risk factors and depressed peer and individual protective factors at the community level to guide the selection of preventive interventions may be a viable strategy for community efforts to prevent adolescent substance use. (Contains 8 tables.)