Members of historically underrepresented groups—women, African Americans, Latinos, and workers—are serving in American legislatures in increasing numbers. However, legislators wield substantially greater power in the lawmaking process when they hold leadership positions. Incorporation of these groups into leadership positions could indicate fuller political representation, but scholars to date have not assessed how well these groups are represented in leadership. We analyze original data describing the backgrounds of approximately 2,200 leaders in 30 states between 2003 and 2014. The data show that, on average across states, members of these groups are as well represented in state legislative leadership positions as they are in rank-and-file membership, but there is substantial variation across states and across parties. We then ask what factors might explain this variation and explore institutional characteristics, like the number of leadership positions or leader selection methods. The results show that legislative chambers with a higher number of leadership posts tend to have more women in leadership, and that selection through elections is associated with decreased African American presence in leadership. The findings have implications for minority incorporation and influence in American politics.