Significance Interpersonal conflict and violence occur within and between groups around the world. Although not proving causation, this study is significant because it suggests a key psychological mechanism in children’s chronic aggression that might be targeted for intervention: one’s attribution that a peer is acting with hostile intent. When children attribute hostile intent to peers, they are more likely to predict they would react aggressively than when they attribute benign intent. Differences in this tendency statistically account for differences in future chronic aggressive behavior problems across children, as well as differences in chronic aggressive behavior problem rates across ecological-context groups. Identifying this mechanism could lead to novel interventions, education, and policies that reduce or prevent aggressive behavior.