This article adds to the emergent body of constitutional-theoretical research on populist government. It argues that constitutional analysis has specific importance in explaining the hostility to global legal norms that characterizes many populist or neo-nationalist polities. However, it argues that more classical perspectives in constitutional theory have not provided adequate explanations for this phenomenon. This is because constitutionalism itself misunderstands the sociological foundations of constitutional democracy and it promotes normative models of democracy, based in theories of popular sovereignty and constituent power, which create a legitimational space in which populism can flourish. In contrast, this article sets out a historical-sociological account of national democracy, explaining how democracy has been formed through processes of global norm construction. As a result, the basic subjects imputed to democracy by both constitutionalism and populism only became real on global normative foundations. In advancing these claims, this article presents a global-sociological critique of populism, explaining that populism evolves where the realities of democratic formation enter conflict with the norms of constitutional theory. In so doing, it offers a sociological theory of constitutional democracy that might help to avert democratic self-subversion.