This article suggests that it is in the vicissitudes of the OECD's internal developments that we can better understand how the OECD developed into a global policy actor and reference in education. From an ontological perspective, the article focuses on the three characteristics dimensions of IGOs -- actor, arena, instrument -- and examines how these are constitutive of the OECD, as reflected in the OECD's work in education. The idea of 'dimension' allows the inquiry to move forward from the idea of 'roles' or 'functions' that the organisation, voluntarily or otherwise, chooses to play in a given situation, to develop more textured interpretations, in which the organisation's intergovernmental and organisational facets, besides its acknowledged political facet, are also taken into account. The historical analysis focuses on the early 1970s. It demonstrates the overlapping and interplay between the three dimensions, as well as their constitutive effects on the OECD's work. It is the 'lively' pluridimensionality of the OECD that has enabled the educational activities to prove their way within the organisation. The OECD's pluridimensionality reveals that the organisation does not operate in a vacuum, and that it is neither a monolithic nor an insulated organisation.