This paper examines the role of the state in the development of French Sociology after 1945. This role was important in the institutionalization of the discipline. It favoured the creation of research teams, resarch centres or laboratories. The State favoured the funding of french sociology too. This funding, in the form of research contracts with various public bodies, has contributed to the emergence of the figure of the expert and, more broadly, to the involvement of sociologists in sectoral policies.