This research examines the opposing theories that high self-esteem is responsible for aggression and that low self-esteem is responsible for aggression. Our findings suggest that both theories may be correct. Targets' self-esteem and self-reported physical aggression were assessed; additionally, targets' roommates reported their esteem for the target. In support of both theories, self-esteem was related to aggression in a curvilinear fashion, such that very low and very high self-esteem people were more likely to report physical aggression than moderate self-esteem people. This phenomenon was partly qualified by interpersonal context; specifically, participants who thought more positively of themselves than their roommates thought of them as well as participants who thought less positively of themselves than their roommates thought of them reported higher levels of physical aggression. Those whose self-esteem (low or high) corresponded to roommates' esteem of them did not report physical aggression. These findings inform psychological theories of aggression, especially regarding self-views and interpersonal reality.