In this article, we analyse the challenges and impact of the new territorial reform on the design of social policy and the details of its implementation at local level. The law on the new territorial organization of the Republic (NOTRe, 2015) — following the law to modernize territorial public action and affirm the status of large cities (MAPTAM, 2014) and the law on the delimitation of regions (2015) — once again raises the question of the future role of the region in social policy. We propose a critical perspective of this reform, which refocuses the action of the départements on solidarity while maintaining their role as “leader” in an uncertain position between the consolidation of large regions and the increasing importance of intercommunal and metropolitan powers. However, the plan to transfer some social jurisdiction to metropolitan entities raises more questions than it answers, and reveals the very limited commitment of these entities to this field. The decentralisation issue ultimately lies less in the established distribution structure of policy responsibilities than in the gradual elaboration of a new social response, replacing the usual vertical and sector-based interventions with a more transversal and decompartmentalized approach which is not only corrective and restorative, but also more preventive and inclusive.