Data from 44 societies are used to explore sex segregation by field of study. Contrary to accounts linking socioeconomic modernization to a “degendering” of public‐sphere institutions, sex typing of curricular fields is stronger in more economically developed contexts. The authors argue that two cultural forces combine in advanced industrial societies to create a new sort of sex segregation regime. The first is gender‐essentialist ideology, which has proven to be extremely resilient even in the most liberal‐egalitarian of contexts; the second is self‐expressive value systems, which create opportunities and incentives for the expression of “gendered selves.” Multivariate analyses suggest that structural features of postindustrial labor markets and modern educational systems support the cultivation, realization, and display of gender‐specific curricular affinities.