The effects of Aggression Replacement Training were explored in a group of Dutch violent young men ages 16 to 21 years, who were obliged by the court to follow a treatment program in a forensic psychiatric outpatient clinic. To evaluate the training, patients completed a set of self-report questionnaires at three moments in time: at intake/before a waiting period, after the waiting period/before the training, and after the training. During the waiting period, the patients did not change on most measures, although they displayed a significant increase in anger. The patients who completed the therapy scored significantly lower on psychopathy than the patients who dropped out. The training produced significant decreases in physical aggression and social anxiety and showed trends toward a decline in self-reported hostility, general aggression, and anger. After the training, the patients scored comparably with a reference group on measures of hostility and aggressive behavior. Altogether, these results provide tentative support for the efficacy of the Aggression Replacement Training for violent outpatient settings.