This study examined the role of aggressiveness and parenting in the development of children’s moral self-concept. Participants were 198 elementary school children and their parents (M = 8.65 years, SD = 2.44). Participants completed a structured moral self puppet interview and a questionnaire about their relationship to parents. Parents completed a questionnaire measuring their children’s aggressiveness. Results indicated that children who were more aggressive scored significantly lower on the moral self than did less aggressive children. Positive parent–child relationships predicted higher scores on children’s moral selves. Finally, negative parent–child interaction moderated the effect of aggression, with negative associations between aggression and children’s moral self exacerbated at high levels of negative parent–child interaction, and attenuated at lower levels. This study elucidates the importance of aggression and parenting in accounting for differences in children’s moral self.