One of the most significant developments in international relations theory in the past decade has been the reconciliation of radical post-positivist theorists to realism. This article examines the causes and consequences of that reconciliation. It argues that while advances in the history of international thought have prompted substantive re-evaluations of the work of past realist thinkers, including that of Carl Schmitt and Hans J. Morgenthau, the reconciliation of radicalism and realism has occurred because of the radicals' realisation of their common anti-liberalism. Drawing upon the work of Stephen Holmes, the article concludes with a discussion of the implications of the rise of anti-liberalism among international relations theorists.