Abstract
This study uses data from a series of laboratory experiments to provide a comprehensive analysis of gender differences in performance caused by two different dimensions of competition –rivalry for resources and status ranking. It also examines two mechanisms behind such differences. The results indicate that in the absence of any competitive dimension the performance difference between men and women is not statistically significant at the usual levels. Any competitive dimension, however, leads to women performing statistically significantly worse than men. These results are explained by the two mechanisms: (1) men’s beliefs that they are better than women under competition, and (2) women’s adherence to a prescribed stereotype of not harming others. This suggests that gender differences under competition are endogenous to situational contexts.