Gender and LGBTQ+ representation across college majors and achievement levels using nationally representative US data.

Gender segregation across college majors persists, yet how these patterns vary across achievement levels and intersect with LGBTQ+ identity remains unclear. We examine whether field cultures and social norms may create 'in-group benefits' for lower-achieving members of field-specific majority groups. Using two nationally representative US longitudinal datasets (the High School Longitudinal Study, n = 6,340; and the Baccalaureate and Beyond Class of 2016, n = 12,950), we estimate relative representation across majors spanning male-majority physics/engineering/computer science to female-majority health fields. Across datasets, representation is most polarized among lower-achieving students, particularly in male-majority fields, where lower-achieving straight-cisgender males are overrepresented relative to lower-achieving straight-cisgender females (relative ratio, 2.62; 95% confidence interval, 2.29-3.00), while this representation gap is smaller among higher-achieving students (P < 0.001). The patterns persist after adjusting for achievement, coursework, interests and aspirations. In female-majority fields, evidence for analogous in-group benefits is mixed across models vis-à-vis LGBTQ+ identity. The findings suggest that the forces shaping field-level sorting operate differently across achievement levels, with implications for talent development and broadening participation.