Although incivility is an increasing concern among scholars and the public, explanations for this phenomenon sometimes overlook the role of computer‐mediated communication. Drawing from the social identity model of deindividuation effects (SIDE), we consider incivility as a form of identity performance occurring in the visually anonymous contexts that are typical online. Specifically, we examine partisan political identities and intergroup factors as predictors of incivility in a newspaper discussion forum. Contrary to expectations, conservatives were less likely to be uncivil as the proportion of ingroup members (i.e., other conservatives) in the discussion increased and less sensitive to incivility directed at outgroup members (i.e., liberals) than were nonconservatives. Audience members had more extreme evaluations of uncivil comments made by partisans than nonpartisans.