In the twenty years after 1945 both the United States and Britain created public funding regimes for social science, through the National Science Foundation (NSF) and the Social Science Research Council (SSRC) respectively. The historical and political contexts in which these institutions were founded differed, but the assumptions about social science concurred. This article uses archival sources to explain this comparative pattern. It is argued that the political context in both countries played a key role in the development of the two research agencies. In each country the need politically to stress the neutrality of social research – though for different reasons in each case – produced a bias towards positivist scientific methodology, untempered by ideology. This propensity created the trajectory upon which each country's public funding regime rests.