In this paper, we exploit new data to assess gender differences in pre-labor market specialization among the college educated and highlight how those differences have evolved over time. We highlight new results pertaining to gender differences in the mapping between undergraduate major and subsequent occupational sorting. To perform our analysis, we introduce new indices in potential wage space that measure gender differences in major choice and separately the subsequent occupational sorting conditional on major choice. We highlight that women both choose majors with lower potential earnings (based on male wages associated with those majors) and that they then sub-sequently sort into occupations with lower potential earnings given their major choice. We highlight that these differences have narrowed over time but recent cohorts of women still choose majors and occupations with lower potential earnings. Differences in undergraduate major choice explains a substantive portion of gender wage gaps for the college educated above and beyond simply controlling for occupation. Collectively, our results highlight the importance of understanding gender differences in pre-labor market human capital specialization and the mapping between college major and occupational sorting when studying the evolution of gender differences in labor market outcomes over time.