OBJECTIVE:: This research seeks to identify the sources of, reactions to, and tactics that nurses use to address aggression in the workplace. BACKGROUND:: Models explaining aggression have limitations and do not address the tactics that victims use when confronted with aggression. METHODS:: Personal interviews were conducted with 47 RNs at a large university hospital. Grounded theory techniques were used in the analysis. RESULTS:: Tactics varied by the type of perpetrator being addressed. Coworkers were likely to be the aggressor, with patient care technicians being the most commonly identified aggressor toward RNs. CONCLUSIONS:: Knowing the sources, reactions, and tactics used in response to aggression is necessary to support the development of preventive and responsive strategies from individual and organizational perspectives.