Although a great deal of research has examined specific behaviors that positively affect leaders' negotiation processes and outcomes, there has been considerably less attention devoted to stable characteristics, psychological or physical, that might also influence outcomes at the bargaining table. In the current research, we identify a measureable physical trait — the facial width-to-height ratio — that predicts negotiation performance in men. Across four studies, we show that men with greater facial width-to-height ratios are less cooperative negotiators compared to men with smaller facial ratios. This lack of cooperation allows men with greater facial width-to-height ratios to claim more value when negotiating with other men, but inhibits their ability to discover creative agreements that benefit all negotiating parties. These results provide insight into the factors linking leadership, facial structure and conflict resolution.