We conducted an archival study at a coeducational Catholic university to test the proposition that single-sex secondary education predicts lasting differences in college majors. Men from single-sex schools were more likely to both declare and graduate in gender-neutral majors than those from coeducational schools. Women from single-sex schools were more likely to declare gender-neutral majors, but were not different from their coeducated peers at graduation. A second study was conducted with a sample of first-year students to examine the correspondence between egalitarian attitudes, single-sex secondary education, and major choice. Egalitarianism was higher in students in nontraditional majors, but did not correspond in expected ways with single-sex education. Men from single-sex schools were less likely to hold egalitarian attitudes about gender roles, whereas women from single-sex and coeducational high schools did not differ in egalitarianism. Taken together, our results raise questions about the potential of single-sex high schools to reduce gender-stratification in professions.