Compared to the “solidarist” policy outlined at the end of the nineteenth century, the social program introduced at the Liberation of France after the Second World War is of a different nature. It aimed to construct a form of collective interdependency, a true social cohesiveness. The program of the National Council of the Resistance, entitled Happy Days (a literal translation of “Les jours heureux”), lays out the general features that will be fundamental to the new social security system. The ambition of the founding fathers is to organize nothing less than a just and united society with social institutions that will promote individual and collective emancipation. In this initial phase, however, social security as an institution was not free from ambiguity. Two different conceptions of social protection were more or less explicitly enunciated. Because of these ambiguities, which became accentuated over time, the system has inherited its current composite nature. It hesitates between offering universal protection and protection limited to those in work. This indetermination is the origin of later deviations.