We undertook the first broad-scale quasi-experimental evaluation of youth outcomes in communities using the Communities That Care program (Hawkins, J. D., & Catalano, R. F., Jr. San Francisco, CA, USA: Jossey-Bass Inc, Publishers, 1992a), which targets adolescent problem behaviors. We evaluated 15 risk factors and 6 outcomes (substance use and delinquent behaviors) for 38,107 youth in 2001 and 98,436 youth in 2003 in Pennsylvania schools. Multilevel analyses compared student reports in communities with CTC programs to comparable communities without CTC, while controlling for level of poverty in the community. Results favored the CTC communities at greater than chance levels in terms of lower rates of some risk factors and outcomes. In a follow-up analysis, CTC community grade cohorts were included only if the grade cohort was expected to benefit from a CTC sponsored program (based on timing of program implementation and target age of the program). Evidence of CTC effects for grade cohorts that received evidence-based programs was even stronger. These findings suggest that community coalitions can affect adolescent public health problems at a population level, especially when evidence-based programs are utilized.