The current article aims at analysing the ways the FAJ (a founds in favour of the most excluded young people) is implemented in the framework of the decentralisation law of 2004 (which transfers a large part of competences from the State to the Départements). The study, led in six French Départements, shows that the Conseils généraux are dealing very differently with the FAJ. The elements of analysis (amount of budget, modalities of elaboration of the internal rules, evolution of the relationships with the other disposals and actors) permit to point out the various uses of the FAJ which can be either an isolated tool or a lever to promote an integrated policy. The identified territorial inequalities in the implementation of the FAJ can also be examined in the ways young people may access to the disposal. The examination of the access criteria, the issues considered as relevant (both individual and collective) give us an idea of the deeply contrasted conceptions of the social intervention. In a framework of youth increasing precariousness and of important sociological evolutions of this age of life, the analysis of the implementation of the FAJ raises questions on the conditions to which a youth policy can be built at local level.