The International Seminar on Macroeconomics (ISoM) is an annual conference, which was co-sponsored during 15 years (1978-1993) by the French EHESS and the NBER. This article uncovers the scientific and institutional dynamics unrolling from this cooperation. We argue that macroeconomists gathered by the ISoM contributed greatly to the making of a European network of economists sharing similar professional and intellectual standards. We illustrate how the ISoM stood at the crossroad of two types of ‘internationalisation’ of economics. First, the integration of European national communities and, second, the process of ‘Americanisation’ of economics. While existing literature on ‘internationalisation’ focuses on the national level, our contribution investigates the European level. Moreover, we unveil how two research programmes in macroeconomics (namely the disequilibrium theory and large-scale macroeconometric modelling) played a significant role in this process.