This study (a) examined the role of anger rumination as a mediator of the relation between social anxiety and the experience of anger, hostility, and aggression, in the general population, and (b) evaluated the degree to which the presence of autism spectrum disorder characteristics moderates the indirect influence of anger rumination. We then explored whether social cognition and perseveration characteristic of autism spectrum disorder uniquely accounted for the predicted moderation. In this survey study of young adults (n?=?948), anger rumination mediated the relation between social anxiety and hostility, as well as verbal and physical aggression, as predicted. Greater autism spectrum disorder characteristics augmented the effect of social anxiety on hostility and physical aggression by increasing the effect of anger rumination, but not by increasing the effect of social anxiety on anger rumination. Implications for developing treatment approaches that target hostility and aggression among young adults who may not be formally diagnosed but have characteristics of autism spectrum disorder are discussed.