This paper investigates how achievement of university peers affects men’s and women’s course choices, major choices, and labor market outcomes. Exploiting random assignment of students to sections, we find that higher-achieving male peers cause men to take more mathematical courses. This effect persists in the labor market where men end up in higher-paying jobs. Women with higher- achieving male peers choose fewer mathematical courses and majors. These women end up in jobs where they earn less but are more satisfied. Thus, it is not obvious whether women’s exposure to
high-achieving male peers benefits or harms them.