Emotions play an important role in conflict resolution. Past work has found that negotiators tend to concede when confronted with anger. We argue and show that this effect occurs in conflicts about interests, but not in conflicts about values. In value conflicts that are more closely tied to a person's values, norms, and identity, expressions of anger are likely to backfire. We demonstrate that people deem expressions of anger more unfair in value conflicts than in interest conflicts (Study 1) and that they are more likely to engage in retaliatory and escalatory behaviours when confronted with an angry reaction in the context of a value issue rather than an interest issue (Study 2).