Vigilantes monitor their social environment for signs of wrongdoing and administer unauthorized punishment on those who they perceive to be violating laws, social norms, or moral standards. We investigated whether the willingness to become a vigilante can be predicted by grandiose self-perceptions about one’s communality (communal narcissism) and enjoyment of cruelty (sadism). As hypothesized, findings demonstrated both variables to be positively related to becoming a vigilante as measured by reports of past and anticipated vigilante behavior (Study 1) and by dispositional tendencies toward vigilantism (Studies 1 and 2). We also found communal narcissism and sadism predicted the perceived effectiveness of vigilante actions exhibited by others (Study 2) and the intention to engage in vigilantism after witnessing a norm violation (Study 3). Finally, Study 3 also demonstrated that the tendency for communal narcissists and sadists to become a vigilante might vary based on the expected consequences of the observed norm violation.