Objectives: Given the high rates at which adolescents engage in violence, the strong link between adolescent and adult violence, and the financial and social costs of violence, the prevention of violent behavior is a national priority. Methods: The authors conducted a comprehensive review of evaluations utilizing quasi-experimental or experimental research designs to assess violence reduction. Results: Seventeen interventions were identified as producing a significant reduction in youth-perpetrated physical or sexual violence. The interventions were varied in terms of targeted age groups, content, strategies, and length of programming, and included programs focusing on individual, peer, school, family, and community factors. Conclusions: Widespread use of effective interventions such as these, across settings and development, and implemented with fidelity, is likely to substantially reduce youth violence. Continued evaluation of violence prevention programming is also needed to increase the number of options available for replication and establish effects on diverse populations. (Contains 1 table.)