When does expressing anger in negotiations lead to concessions? Although research has begun to address this question, it has not yet examined the influence of the negotiation context. We propose that the effect of expressing anger depends on the competitiveness of the negotiation situation. Specifically, when the negotiation situation balances cooperative and competitive elements, expressing anger elicits larger concessions than no anger, and responses are driven by cooperation-inducing strategic inferences (e.g., a perception that the anger expresser is tough and threatening). However, when the negotiation context is predominantly cooperative or predominantly competitive, expressing anger does not elicit larger concessions than no anger, and responses are driven by cooperation-inhibiting affective reactions (e.g., reciprocal anger and a desire to retaliate against the anger expresser). Results from two computer-mediated negotiation experiments using different negotiation scenarios, different manipulations of the competitiveness of the situation, and different subject populations supported our hypotheses.