This paper discusses the findings of the National Academy of Sciences Panel on the Understanding and Control of Violent Behavior, established to review the current status of research in violence; the extent and nature of violence in this country; promising opportunities for prevention; and areas in which further research and better measures are needed, particularly to identify causes and additional opportunities for prevention. Key findings include: The level of violent crime in this country has reached high, though not unprecedented levels; between 1975 and 1989, harsher prison sentencing prevented some violent crimes through incapacitation and deterrence, but crimes by persons still in the community offset those preventive effects; and in addition to an effective criminal justice response, the strategy for violence reduction should include preventive interventions directed at the multiple factors affecting the risk of violence.