Gender, competitiveness, and task difficulty: Evidence from the field

•This study examines the gender gap in competitiveness in an educational setting.•We test whether this gap depends on the difficulty of the task at hand.•We find that women are significantly less likely to select the tournament scheme.•The gender gap in tournament entry is sizable when the tasks are relatively easy.•The gender gap in tournament entry is much smaller and insignificant when the tasks are difficult.