This article studies the history of economic sciences in France during the period 1945–1958. It situates the doctrinal history of the corps of associate professors within the broad and rich history of scientific policies that marked these years of reconstruction. In 1942, the corps of political economy professors in the faculties was composed of 16% liberals, 13% socialists, and 69% interventionists. In 1958 the distribution was as follows: 9% liberals, 26% socialists, and 65% interventionists. Under the Fourth Republic, the civil service exams consolidated, on the one hand, the new interventionist orthodoxy of the faculties—established between1877 and1942—and the decline of the liberals; and on the other, established a socialist school, including a group of Marxist professors, a doctrine hitherto absent from law faculties. These developments confirm that the demand for expertise from administrations and governments, along with public funding of research in economic sciences, inevitably shaped the nature of the knowledge produced and the questions that economists posed to reality. Indeed, two events coincided: on the one hand, the establishment of a government of science and by science, and on the other, the recruitment of professors who, through their specializations—planning tools and economic policy—developped the governance techniques required by political power.