This chapter introduces the book and its context. It argues that the philosophical Pragmatist’s commitment to experimentalism and learning, and the social and political theory emerging from that, is well placed to address global security, climate and health challenges. To recognize that, International Relations and ‘new constructivism’ has to bring Pragmatism in from the margins. The chapter summarizes IR’s current relationship to Pragmatism focusing on the methodologies of analytical eclecticism, the historical accounts of the progressive foreign policy agenda that classical Pragmatism informed and the attempts to use Pragmatism as a tool of analytical and normative analysis. The chapter sets three questions, which structure the rest of the book: (1) what can classical Pragmatism bring to debates in IR, including those centred on the perennial question of how norms, practices and interests interact to influence international society and its practitioners? (2) How, if at all, should international practices and practitioners adapt in the face of pressing global security, climate and health challenges? (3) Given the Pragmatist answer to these first two questions, what normative conclusions can we come to about actual practice in contemporary international society? A summary of how each chapter contributes to answering these questions is provided.