Of the many changes that transformed the French economy after the Second World War, one of the most marked was the new interventionist role played by the state. In contrast to the laissez-faire economic liberalism of the Third Republic, which had responded to the demands of a narrow but sizeable agricultural lobby group, and to the authoritarian management of Vichy that had served the interests of the German occupation forces and the Nazi war economy, the postwar state was to serve the interests of a much wider range of groups in France demanding economic as well as political security. Under a series of reforms enacted between 1944 and 1948, the structures and instruments that would enable this newfound scale of state intervention in the economy were put in place. Some were inherited from the structures introduced by the Vichy state; others reflected the political aspirations of the resistance groups. Together, the reforms included an extension of the nationalization programme begun under the Popular Front government to include coal, electricity, the main deposit banks, the remaining privately owned firms in the aero engine industry, the Renault car and truck maker and all the air transport companies. These nationalizations were in line, in terms of both the type of industries targeted and the method of implementation, with those introduced in other European states. Where the French were different was in creating a system of indicative planning that, unlike the Soviet system, was designed to operate within a parliamentary democracy. The entire apparatus of state intervention that was put in place was designed to make economic policy-making more democratic than had previously been the case.

It was not just the economic liberalism of the Third Republic that was swept away after 1945, but the entire constitution. Although it had been set up in response to French defeat in the war with Prussia and had survived the First World War, the Third Republic was now associated with decline and defeat. That there would be no return to it in any shape was confirmed by the results of a referendum held five months after the end of the war in Europe.