Historical accounts of the social sciences have too often accepted local or national institutions as a self-evident framework of analysis, instead of considering them as being embedded in transnational relations of various kinds. Evolving patterns of transnational mobility and exchange cut through the neat distinction between the local, the national, and the international, and thus represent an essential component in the dynamics of the social sciences, as well as a fruitful perspective for rethinking their historical development. In this programmatic outline, it is argued that a transnational history of the social sciences may be fruitfully understood on the basis of three general mechanisms, which have structured the transnational flows of people and ideas in decisive ways: (a) the functioning of international scholarly institutions, (b) the transnational mobility of scholars, and (c) the politics of transnational exchange of nonacademic institutions. The article subsequently examines and illustrates each of these mechanisms.