This article sets forth the main elements of the conceptual framework for the overall approach to the Programme for International Student Assessment (PISA) taken in this special issue. PISA is here examined as a (knowledge for policy) regulatory instrument made by intertwined cognitive and social practices, and involving multidirectional flows of knowledge and policy elements. Additionally--and using materials from a study on the fabrication of PISA--the article gives closer attention to the process of gathering and coordinating the social worlds involved in the making of the instrument, to the plasticity of knowledge for policy and to the fictions--which the instrument carries--regarding education and its governing practices. As a whole, the article relates to the ubiquity of PISA--that is, its conspicuous albeit not similar presence in various geopolitical territories and discursive spaces. Fabricated under the auspices of the Organisation for Economic Cooperation and Development, by bringing together individuals and organisations from various social spaces, its materials and texts generated often reach national and local policy and knowledge contexts, where different social groups have interests in them and are using them differently, though attached to PISA's dicta on regulatory processes. (Contains 17 notes and 3 figures.)