This digest reviews a variety of the policies, programs, and practices to prevent youth violence so that local leaders can base decisions on the experience of other communities. The effectiveness of school violence prevention initiatives is increased by public policies that reinforce their message and by community programs that attempt to prevent or relieve youth violence. Antiviolence policies and programs in the schools run the gamut from general educational improvement to interventions that target specific types of illegal or antisocial behavior. The most effective, whether for overall school improvement or school safety policies, are directed by a clearly defined administrative entity and have line-item budgetary status. Prevention strategies, which may include student monitoring and other security measures, are among the most commonly used approaches. Antiviolence and antigang strategies that involve instruction in conflict management are among the most effective programs. The components of successful programs vary, but the most effective rely on accurate assessment of the problem, use of community resources, early intervention, consistent enforcement, and persistence. (Contains 18 references.) (SLD)