This book tells the story of the life and work of L. Susan Stebbing (1885-1943), the first woman Professor of Philosophy in Britain, and the author of a number of popular books, including Thinking to Some Purpose (1939). It traces her professional and personal associations with many of the leading philosophers of her day, including G. E. Moore, Bertrand Russell, A. J. Ayer and Ludwig Wittgenstein. Stebbing's early writings were concerned with formal logic, but she came increasingly to believe in the importance of exposing misleading uses of language in, for instance, popular works of science, advertisements, newspaper editorials and political propaganda. This book considers the historical developments and the personal, social and political commitments that contributed to this belief. It also assesses Stebbing's work in the light of subsequent developments both in analytic philosophy and in linguistics, and suggests that it has important contributions to make in both fields.