This study examined the hypothesis that the association between hostile attributions and aggressive behavior with peers is moderated by children's temperament among three samples of preschoolers. Hostile attributions were assessed through videotape-based and story-based laboratory procedures. Maternal ratings and laboratory-based assessment provided the measures of temperament, and children's teachers completed ratings of aggression. Results revealed significant interaction terms between hostile attributions and temperament in the prediction of aggression. For children rated well or moderately skilled in self-regulation there was no association between hostile attributions and aggression. For children rated as poorly skilled in self-regulation making hostile attributions was significantly associated with aggression. This pattern of associations was particularly apparent for boys. Mother-rated items used to compute emotions regulation composite is appended. [This research was supported by a University of Tennessee at Chattanooga Foundation research grant.] (Contains 5 tables and 3 figures.)