Women wrote on the myriad problems of international relations, generating a multiplicity of forms of international thought. The introductory chapter to this edited volume, the first book-length attempt to recover and analyze the intellectual work of a range of historical women thinkers, asks how we might think systematically about this intellectual history. What assumptions about these categories – women, international, and thought – should we make? The contrast between the presence of historical women in the multiple forms and sites of international thought and their absence in the relevant intellectual and disciplinary histories suggests that it is high time to begin confronting these questions. This book retrieves as well as analyzes women’s international thinking, and broadens and deepens what are currently taken to be the accepted practices and locations of international thought in both History and International Relations.