Historiography often describes the inter-war period as a phase that fostered a transnational «epistemic community» of social scientists and thus largely contributed to the internationalization of social policy. In this context, the American social sciences appear to have played a key role in the international diffusion of empirical social research. However, from the opposite point of view, we can observe that just after World War I social scientists in the United States tended to abandon traditional forms of the transatlantic knowledge transfer, and to p'ivilege national approaches to scientific research. From this perspective, focusing on sociology, this paper intends to show that the interwar period was characterized by two contrasting developments: while certain specialized discourses were proof to the increasing internationalization, key segments of American soc ology developed towards nationalized research agendas. [ABSTRACT FROM AUTHOR]