--- - |2 Abstract This study investigated the moral socialization strategies that mothers use in conversations about their children's experiences of harming their siblings as compared with their friends. The sample included 101 mothers and their 7‐, 11‐, or 16‐year‐old children; each dyad discussed events when the child (a) harmed a younger sibling and (b) harmed a friend (order counterbalanced). Analyses indicated that when children harmed their siblings, mothers were more likely to emphasize their children's wrongdoings, the effects of harm, insights about the self and de‐escalatory strategies. In contrast, when children harmed their friends, mothers mitigated their responsibility for harm, focused on consequences for the relationship, and discussed reparative strategies. These patterns were not typically moderated by age; that is, distinctions in socialization strategies across relationships were largely maintained across middle childhood and adolescence. Findings provide empirical support for recent theorizing that parents respond flexibly to children's varied experiences of harm, and suggest that moral socialization practices take into account the unique features of children's relationships with different types of age‐mates (e.g., the relatively uninhibited quality of sibling harm and the voluntary nature of children's friendships). - Social Development, Volume 27, Issue 4, Page 910-923, November 2018.