The existence of global social (security) policy hinges on a shared epistemic space in which schemes or systems of social security can be distinguished and compared. This first empirical chapter examines practices of infrastructuring that contributed to a shared ontological framework in the interwar years and during WWII. It addresses, first, the process of theorizing on common models of social security; second, the establishment of common methods of statistics as necessary literary practices to enact a shared language for epistemic infrastructures; third, the contested production of similarity between institutions of social policy as part of the International Survey of Social Services; and fourth, the development of the overarching category of ‘social security’ that provided a normative orientation for social policymaking. The chapter is particularly concerned with the political economy of knowledge production.