Relatively little is understood about the role of hostile attributions in children's use of relational aggression with peers, or about the impact of family processes on children's attributions about ambiguous provocations. This cross-sectional study investigated associations among hostile attributions made by children, mothers, and fathers, and children's use of relational aggression with peers. The sample included 91 children in Grades 3-5 (43 girls), and their mothers (n = 90) and teachers (n = 88). Fathers also participated for a subsample of children (n = 53). Results showed that relational aggression is associated with a hostile attribution bias in children and parents, although findings varied as a function of gender of parent and child, provocation type, and informant of aggression. Overall, mothers' attributions were more closely related to daughters' attributions and aggressive behavior than to sons'. Implications of these findings for social information processing models and family-focused prevention of relational aggression are discussed. (Contains 5 tables, 2 figures, and 1 note.)