Research indicates that children's moral judgments with respect to aggression or causing harm develop relatively early. Further, children's negative evaluation of aggression are not based on the existence of rules or sanctions nor by the dictates of authorities or group consensus. Rather, avoidance of harm and concern for others' welfare were the most significant justification given by children. With regard to moral issues, children's judgments were obligatory, nonalterable, and generalizable. Studies of children's concepts of convention, however, show these to be contingent on rules, authority, or institutional practice. In judgments on conventional issues, children take a relativistic orientation and evaluate conventions by their social context. In children and adolescents, aggression is directly related to moral judgment and indirectly related to concepts of convention: given sufficient conventional inducements, experimental subjects would aggress, while still expressing concern about the harm inflicted on another. Finally, psychological attributions also have been implicated in aggression. These findings suggest that preventing aggression requires fostering development of moral judgments and educating children to coordinate these with their attributions and their understanding of conventional social systems. 35 references.