Most Realists today oppose far-reaching global reform on the grounds that it represents unrealistic and potentially irresponsible ‘utopianism’. An earlier generation of mid-century Realists, however, not only supported serious efforts at radical international reform but also developed a theoretically impressive model for how to bring it about. They considered the possibility of post-national political orders and ultimately a world state as desirable long-term goals, but only if reformers could simultaneously generate the thick societal background (or what they called ‘supranational society’) required by any viable order ‘beyond the nation state’. As they fail to engage constructively with proposals for global reform, present-day Realists betray their own intellectual tradition. By reconsidering the subterranean legacy of Realist reformism as advanced by mid-century international thinkers (e.g. E.H. Carr, John Herz, Hans Morgenthau, Reinhold Niebuhr, and Frederick Schuman), the essay provides a revisionist reading of the history of twentieth-century international theory, while also highlighting its significance for ongoing debates about global reform.