Despite recent progress in preventing involvement in gangs during childhood and adolescence and in reducing serious and violent gang crime, the complexity of the youth gang problem defies an easy solution or single strategy. Current knowledge about which programs are effective in preventing and reducing youth gang problems is limited. The most effective program model will likely prove to be a combination of prevention, intervention, and suppression strategies integrated in a collaborative approach, supported by a management information system, and validated by rigorous evaluation. Communities across the country are undertaking collaborative efforts to deal with youth gangs, but few of these programs and strategies are being evaluated. State and local governments must undertake systematic examination of their youth gang programs and strategies. The knowledge gained about what is effective and what is not will benefit not only their own communities, but also communities across the Nation.