The Organisation for Economic Cooperation and Development (OECD) has risen to prominence as one of the most influential international organisations in the world, in large part due to its country reviews and comprehensive comparative testing portfolio. This article starts from two proposition: (1) that fields of tension and antagonisms lie beyond the universalistic rationality of the consensual world-visions apparently supported by the OECD, and (2) that, at least in the field of transnational education policy, the role of quantification has played an essential part in shaping and thus governing the field. The article takes a historical perspective in analysing and substantiating these propositions during the first decade of the OECD's existence: the 1960s. The article also considers the inter-organisational relations between the OECD and UNESCO, a competing organisation in terms of defining and shaping education internationally. The article argues that in order to understand the role of international organisations in transnational education governance, one needs to bring together two important, interdependent aspects; first, an empirical sociological analysis of knowledge as produced through the construction of education metrics; second, a sociology of the trajectories and positions of European and national education actors/experts in international organisations that also 'make' the European education policy space.