Despite the public health burden of adolescent substance use, delinquency, and other problem behavior, few comprehensive models of disseminating evidence-based prevention programs to communities have demonstrated positive youth outcomes at a population level, capacity to maintain program fidelity, and sustainability. We examined whether the Communities That Care (CTC; Hawkins and Catalano 1992) model had a positive impact on risk/protective factors and academic and behavioral outcomes among adolescents in a quasi-experimental effectiveness study. We conducted a longitudinal study of CTC in Pennsylvania utilizing biannual surveillance data collected through anonymous in-school student surveys. We utilized multilevel models to examine CTC impact on change in risk/protective factors, grades, delinquency, and substance use over time. Youth in CTC communities demonstrated less growth in delinquency, but not substance use, than youth in non-CTC communities. Levels of risk factors increased more slowly, and protective factors and academic performance decreased more slowly, among CTC community grade-cohorts that were exposed to evidence-based, universal prevention programs than comparison grade cohorts. Community coalitions can affect adolescent risk and protective behaviors at a population level when evidence-based programs are utilized. CTC represents an effective model for disseminating such programs.