Interpersonal violence is a major cause of injury, disability, and death, especially among youth. Evaluations of 15 youth violence-prevention projects are under way. Public health is concerned about health problems that need to be addressed via collective action. Public health involvement in addressing interpersonal violence among youths brings an emphasis on primary prevention, a systematic and scientific process, and integrative leadership. Few quantitative evaluations of violence-prevention projects have been done. The interventions are scientifically based and use a spectrum of strategies. Individually oriented strategies are more common than those directed toward peers, families, schools, or communities. Each project has a rigorous evaluation design. Twelve are randomized. Sample sizes range from 180 to 10,000. Participants range in age from 5 to 18 years, although most are in the middle-school years (11-14 years). At baseline, intervention and comparison groups are similar. Baseline data demonstrate high frequency of violent behavior, weapon carrying, and exposure to violence among the youthful participants. Field intervention and evaluation research is difficult and expensive. Difficulties encompass organizational programatic, and scientific issues; these difficulties reduce scientific interest and financial support for projects such as these. Public health has an important role to play in reducing violence. These projects will make important contributions to that task.