Past explanations of violence have characteristically paid more attention to the issues of social conditions and psychocultural stimuli than to the issue of timing. Timing is the focus of this paper in which a differential equation model of the temporal diffusion of violence is developed. This model is derived from behavioral generalizations which indicate that aggression is both instigated and inhibited via direct and vicarious learning. The parameters of the model provide measures of the instigation and inhibition processes that take place throughout an outbreak. Twenty-five data sets representing a wide variety of collective outbreaks of violence are used to test the empirical fit and to evaluate the credibility of the assumptions of the model. The model describes the overtime distribution of incidents quite accurately and the assumptions and implications of the derivation appear to be consistent with the cultural conditions surrounding the outbreaks.