This article argues that deterrence theory can be applied to counterterrorism. Doing so requires broadening the traditional concept of deterrence by punishment, expanding deterrence by denial to include defense, mitigation, and strategic hindrance, and developing deterrence by delegitimization to influence the political, ideological, and religious rationales informing terrorist behavior. In practice, deterring terrorism requires tailoring threats against state and individual facilitators, diffusing the intended consequences of terrorism, and manipulating terrorist self–restraints. When these and other deterrent leverages are applied simultaneously against various actors and processes involved in terrorism, coercion can be achieved.