This article examines the career of activist Frances Kellor (1873–1952), as an important figure among a small group of female pioneers who, prior to 1920, chose to forgo the segregated women’s political cultures of settlement houses, reform organizations, and the suffrage movement, to compete head-on with men in government and party politics. It describes the mixed success of Kellor’s early career efforts to acquire political power, then examines in detail her most visible institutional appointment as Chief of the Progressive Service, in Theodore Roosevelt’s breakaway Progressive Party (1913–1914). The article argues that earlier accounts of the Service have depicted Kellor as an unempathetic taskmaster and negative force, ignoring some primary source evidence that she operated in the face of a hostile campaign by male subordinates to unseat her. It suggests there are grounds to reappraise her performance in this groundbreaking role. It discusses Kellor’s own, later reflections on the masculine realm of public affairs, and how early pioneers in the long, slow process to integrate men and women in political and government institutions were (inevitably) unable to replicate the legislative successes of Progressive Era female pressure group politics.