We leverage variation in the adoption of coeducation by U.S. women's colleges to study how exposure to a mixed-gender collegiate environment affects women's human capital investments. Our event-study analyses of newly collected historical data find a 3.0-3.5 percentage-point (30-33%) decline in the share of women majoring in STEM. While coeducation caused a large influx of male peers and modest increase in male faculty, we find no evidence that it altered the composition of the female student body or other gender-neutral inputs. Extrapolation of our main estimate suggests that coeducational environments explain 36% of the current gender gap in STEM.
Keywords: I21; I23; I24; J16; J24.