This article examines the role of social scientific expertise in socialist Czechoslovakia. The first section centres on the 1950s, when the new social sciences that helped build the institutions and rules of the new regime were established. The roles of social scientists as experts are analysed during the reform era of the 1960s and the so-called consolidation regime of the 1970s. In the final part of this text, the 1980s are characterised as a period when the unequal alliance of the social sciences and the socialist state fell apart.