Women remain significantly underrepresented in positions of power and have limited access to the most prestigious policy areas. Drawing on the political economy of committee assignments, several theoretical approaches could explain why gendered patterns in access to political offices persist. We assess the most prominent theories using unique fine-grained data on members of German state parliaments from 1948 to 2016 and introduce several measures of committee prestige. Using regression, matching and decomposition techniques, we show that observable factors such as qualifications, experience, electoral incentives and structural elements contribute little to gendered committee assignments. Moreover, the increase in the number of women in national parliaments and their growing expertise and experience does not significantly change this pattern. Marginalization remains stable over time, between East and West Germany and across the main parties. We conclude that women remain systematically disadvantaged in the political decision-making process, with unequal access to power.