A community's past history, current stress, and a precipitating event can combine to produce violence, as shown by an analysis of police-community relations in previous urban disorders. In more than half the riots studied by the Kerner Commission, a police action triggered the ensuing riot, but the violence was foreshadowed by an accumulation of unresolved grievances by ghetto residents against local authorities. This history shows the importance of preventing violence. Community policing can help prevent violence by reducing the tensions between police and minorities, targeting juveniles for special attention, directly addressing the problems of social and physical disorder and neighborhood decay, and involving citizens in the police process. Evidence from foot patrol experiments in Flint, Mich. indicates that this approach can succeed in preventing riots. Address from which to obtain reference list and list of publications of the National Center for Community Policing.