Over the last three decades, international lawyers and institutions have come to understand constitution-making as an accepted technique of international law and a means of delivering peace and security. In defending this technique from its critics, scholars have drawn on a particular tradition of constitution-making developed in the postwar period and in respect of the Allied occupations of Germany and Japan. That tradition understands constitutionalism as a lawful form of international action, allowing for temporary forms of international rule, and juridically distinct from material concerns. I explore the building of this tradition through the work of three legal scholars: Ernst Fraenkel, Quincy Wright, and Carl Friedrich.I argue that reimagining constitutionalism for the coming decades requires rethinking this separation between the juridical and the material, as well as asking what constitutionalism demands of the laws governing the global economy.