Understanding the gender dynamics of the U.S. Congress requires attention to all institutional actors, not only the principals (representatives and senators). In this paper, I shift attention to legislative staff, exploring the ways in which gender shapes principal-staff interaction, lobbyist-staff relationships, and staff experience and power. More specifically, I ask where, how, and to what extent gender of major legislative actors (members, staff, and lobbyists) informs the relationships between them, as well as their behavior and influence within Congress. My analysis draws upon in-depth interviews with more than three-quarters of women members of the 114th Congress, and more than two dozen interviews with interest group representatives/lobbyists and members of legislative staff conducted by me and my research team at the Center for American Women and Politics at Rutgers University between 2015 and 2017 (additional interviews with lobbyists and staff conducted before June 2017 will also be included). This analysis will apply feminist institutionalist frameworks and draw upon literature on public entrepreneurship and gendered institutions to illuminate possible sites for institutional disruption and progress in the balance of gender power. It will also reveal new sites for academic research on women’s impact in Congress as managers, staff, and political professionals that move beyond traditional measures of bill sponsorship, floor speeches, and votes, all of which focus on behavior solely of the members themselves.