Men typically express more willingness than women to perpetrate fraudulent acts like lying in negotiations. However, women express just as much willingness in some cases. We develop and test a theory to explain these mixed findings. Specifically, we hypothesize that situational cues that bring about competitive or empathic feelings mitigate sex differences in lying to negotiation counterparts. Results from four experiments confirm our hypotheses. Experiment 1 showed that men and women express equal willingness to lie when negotiating with counterparts toward whom they felt either great competitiveness or empathy. Experiment 2 extended these results by confirming that men only express more willingness to lie absent competitive or empathic feelings towards a counterpart. Experiments 3 and 4 demonstrated that inducing competitive or empathic feelings toward a counterpart eliminated sex differences in lying by leading women to lie more and men to lie less, respectively. Overall, our results suggest that the extent to which negotiators experience competitive or empathic feelings play important roles in whether sex differences in lying in negotiations emerge.