This thesis contributes to the historical sociology of political internationalism through a study of educational institutions. Drawing on the method of multiple correspondence analysis, it explores the paradox of affirming an “international” identity through an essentialist conception of the nation as embodied in the sub-field of IB Schools, a global space of secondary education. The socio-genesis of this sub-field focuses on the construction of an educational curriculum inspired by the internationalist doctrine of the League of Nations (1924-1930 and 1945-1947), which led to an international secondary diploma, the International Baccalaureate (1968). The founders of this private diploma sought to unify a global space for the training of leaders, through a preparatory program for higher education, notably World Literature and World History. Created by an elitist international and founded on the belief that educating elites along the lines of an “international mentality” would make a “better” world, this diploma is provided today in over 3000 secondary schools and 124 countries and presented as an alternative to “national” programs, thereby challenging State monopolies.