Emotions shape strategic conflict dynamics. However, the precise way in which strategic and emotional concerns interact to affect international cooperation and contention are not well understood. We propose a model of intergroup conflict under incomplete information in which agents are sensitive to psychological motivations in the form of anger. Agents become angry in response to worse-than-expected outcomes due to actions of other players. Aggression may be motivated by anger or by beliefs about preferences of members of the other group. Increasing one group’s sensitivity to anger makes that group more aggressive but reduces learning about preferences, which makes the other group less aggressive in response to bad outcomes. Thus, anger has competing effects on the likelihood of conflict. The results have important implications for understanding the complex role of anger in international relations and, more generally, the interplay between psychological and material aims in both fomenting and ameliorating conflict.