International political economy (IPE) was one contender, in its different attempts to include approaches of historical/economic sociology and non-utilitarian political economy in its theoretical toolkit – from Pierre Bourdieu, Granovetter, Polanyi and Georg Simmel to Thorstein Veblen and C. Weber, to mention a few. The rise of post-structuralism, critical constructivism/critical realism, feminism and later postcolonialism in International Relations (IR) provided another opening. Although quite different among themselves, they stand outside the core of IR in similar ways, in that the challenge was driven both by (meta)theoretical concerns and by a different understanding of what matters politically in international relations. In terms of analysis, that means that in international political sociology (IPS) the ‘domestic’ is brought into IR. Yet, this comes in a kind of ‘Weltinnenpolitik’, a world domestic political sphere. In IPS, an open social ontology leads into an analysis of international order as the power politics of constitutive processes.