A central component of evaluating the legitimacy of a representative democracy has to rest in determining the quality of representation received by the various segments of its residents and citizenry. The question of adequate representation for disadvantaged and marginalized groups is particularly relevant, as these are groups that are already subject to additional societal barriers. This project is devoted to explaining why certain members of the U.S. Congress choose to build their legislative reputation around advocating for disadvantaged groups in society, and what sets them apart from their colleagues. Members of Congress work to build reputations for themselves that speak to what their focus is within the legislature, and on whose behalf they are committed to working. But legislators have a finite amount of time and resources, and must make specific choices about the topics on which they develop their expertise and the groups which they champion. Disadvantaged groups, though frequently requiring greater levels of government assistance or protection, tend to have lower levels of political involvement and political capital. Understanding why members of Congress choose to build reputations around advocating for disadvantaged groups offers critical insight into how and when the needs of these group members are prioritized and represented.

I argue that group size within a state or district couples with the general feelings regarding a group to determine the amount of advocacy on behalf of a disadvantaged group that would conceivably be tolerated within a district. Within this “advocacy window,” discretion of the individual member becomes vitally important. To evaluate what drives members to form reputations as group advocates, I use an original dataset of all members of the House and Senate from a sampling over Congresses from the last forty years featuring an innovative variable measuring the extent to which a member’s reputation is rooted in advocating for the disadvantaged. This dissertation offers an important contribution to our understanding of when and by whom representation of the disadvantaged occurs, and also provides broader insight into how members balance personal, partisan, institutional, and electoral concerns in their legislative choices as a representative.