This article describes the networks of experts involved in the fabrication of indicators and benchmarks supporting the Open Method of Coordination led by the European Commission. In studying international expertise, it explores the policy borrowing process and the transfer of knowledge between several agents and institutions at global level. Our hypothesis is that science and policy are not in a discontinuing relationship but represent, through the building of instruments and methodologies of measurement, a corpus of scientific knowledge and normative principles held by representatives of supra-national organizations and States. (Contains 7 maps and 4 notes.)