Employment discrimination statutes generally treat inequality as the product of discriminatory animus, but this approach undertheorizes how institutions construct identities and generate inequality. Drawing on neo-institutionalist theories in sociology, this Article develops a theory of institutional inequality that focuses on how institutions give rise to inequality by reproducing the social patterns and belief systems that existed at the time they emerged. To develop this theory, the Article examines why workplace time standards that disadvantage pregnant women have remained resistant to reform through Title VII and the Pregnancy Discrimination Act. Historical genealogy shows that workplace time standards embody cultural conceptions of gender and work that developed during the transition to modern capitalist production. Courts rely on these institutionalized conceptions of work and gender to interpret antidiscrimination statutes narrowly, reinforcing an oppositional relationship between work and gender and restricting opportunities for social change. The Article concludes by arguing that legal theories, such as the Family and Medical Leave Act, which focus on structural change rather than subordinated identities, are better suited to eradicating workplace inequality that flows from the historical development of work.