We outline a general psychological theory of extremism and apply it to the special case of violent extremism (VE). Extremism is defined as motivated deviance from general behavioral norms and is assumed to stem from a shift from a balanced satisfaction of basic human needs afforded by moderation to a motivational imbalance wherein a given need dominates the others. Because motivational imbalance is difficult to sustain, only few individuals do, rendering extreme behavior relatively rare, hence deviant. Thus, individual dynamics translate into social patterns wherein majorities of individuals practice moderation, whereas extremism is the province of the few. Both extremism and moderation require the ability to successfully carry out the activities that these demand. Ability is partially determined by the activities’ difficulty, controllable in part by external agents who promote or oppose extremism. Application of this general framework to VE identifies the specific need that animates it and offers broad guidelines for addressing this pernicious phenomenon.