The most important lesson learned about youth violence is how complex the problem is and how much work has yet to be done to understand it and reduce it. Indeed, many violence prevention programs have been shown to be ineffective at significantly reducing violence among youth. Moreover, among the programs found to be marginally effective, most outcome data has been based on attitude measurement and responses to hypothetical situations rather than actual changes in youth behaviors. Future research should focus on not only improving violence prevention programming for youth, but also on improving the quality of research designed to evaluate the impact of violence prevention programming. In the meantime, communities are encouraged to seek Federal government assistance in planning, implementing, and evaluating youth violence intervention strategies. The article reviews the research literature regarding the nature and causes of youth violence and then describes the variety of prevention approaches designed to reduce youth violence. These prevention programs are divided into four dimensions: (1) the level of social system they attempt to change; (2) the extent to which they focus on individuals at different levels of risk; (3) the developmental stage of the participants; and (4) program goals. Finally, three programs are reviewed that have been systematically evaluated and found to be at least marginally effective at reducing youth violence: Fast Track, Peacebuilders, and Responding in Peaceful and Positive Ways. Figure, references