The International Baccalaureate (IB) emerged in the 1960s after a significant demand arose for an internationally recognized secondary school-leaving diploma among a subset of the international school community. In tension with the practical demands of producing and sustaining a mobile diploma were underlying liberal-humanist visions of a progressive model of schooling for "international understanding" in an era of embedded liberalism. This article examines three structuring tensions (citizenship, curricular aims and operation) of the "International" of IB and how they were managed by the IB Organization in the founding period (1962-1973). (Contains 1 table.)