Despite popular and official concern about an apparent increase in vigilante activity in the United Kingdom, there has been little serious attempt to conceptualize vigilantism. The author argues that vigilantism has six necessary features. First, it involves planning and premeditation by those engaging in it; second, its participants are private citizens whose engagement is voluntary; third, it is a form of "autonomous citizenship" and, as such, constitutes a social movement; fourth, it uses or threatens the use of force; fifth, it arises when an established order is under threat from the transgression, the potential transgression, or the imputed transgression of institutionalized norms; sixth, it aims to control crime or other social infractions by offering assurances or guarantees of security both to participants and to others. This approach to conceptualizing vigilantism is distinct from attempts to define it as mere "establishment violence" and neither assumes vigilante engagement to be extralegal nor to involve the necessary imposition of punishment on victims. 40 references