The Nation, Psychology and International Politics is a new cultural and political story of the idea of the nation. It begins with the story of the Paris Peace Conference of 1919, and travels back in time to consider the significance of the rise of scientific psychology after 1870. It situates the history of international politics and the idea of the nation in the history of psychology, and reveals, for the first time, the lingering popularity and political importance of a transnational discourse of the psychology of nations that had taken shape in the previous half-century.