Prior research has shown that parental social cognitions are associated with child outcomes such as aggression. The goal of this study was to examine mothers' cognitions about relational aggression, and to explore linkages between mothers' attributions and normative beliefs about aggression and children's competence with peers. Participants included 103 mothers and children in grades 3 through 6. Results showed that mothers viewed relational aggression as more acceptable and normative than physical aggression, and they attributed less responsibility to children for using relational aggression. Maternal cognitions also predicted levels of sternness and disapproval in response to child relational aggression, and children's beliefs about the acceptability of relational aggression, which were associated with children's teacher-rated peer competence. Sex differences in the patterns of associations between maternal cognitions, discipline responses, child norms and peer competence were found. Applications of these results to parent education programs that are focused on relational aggression are discussed. (Contains 1 note, 2 figures and 2 tables.)