This paper tracks the origins of one of Europe’s most ubiquitous instrument: the acquis. Thereby, it aims at initiating a new research programme on the genealogy of Europe’s cognitive and technique equipment. Instead of considering the acquis as a self-explanatory and transparent notion, the paper unearths its rich political meaning, pointing at its instrumental role in shaping a law-centred and supranational definition of Europe. Digging deep into individual and institutional genealogies, the paper follows the methodological entrepreneurs who crafted new knowledge instruments for calculating Europe’s state of affairs (the Celex database) and analyzes the process through which they have progressively acquired a monopoly in the calculation of “the state of the Union”, thereby encapsulating within the very rules of the European game itself a form of “methodological Europeanism”.