Do we need a more social UE – or even a fully-fledged European Social Union (ESU)? An increasing number of empirically oriented social scientists argue that we do. This paper how ESU could be pieced together by r-assembling what is already in place, exploiting in particular the potential of the European Pillar of Social Rights. The paper also discusses the rationales behind the ESU proposal. There is, first, a twofold functional rationale: the EU institutional asymmetry between market making and market corrective goals and policies generates perverse effects; EMU needs a number of social corollaries to effectively perform its mission and functions. But there is a second and equally important rationale, based on political factors. A tenet of political theory is that any territorially organized collectivity cannot survive and prosper without the diffuse support of its members. The latter rests however not only on effectiveness, but also on fairness. Citizens must feel that the territorial government abides by the general norm of somehow representing the collective interest, taking care of all sectors/strata of the population, however weak and peripheral. In order to be politically effective, Social Europe cannot however limit itself to enhancing its institutional strength and policy production. It must become more visible to ordinary citizens and provide them with direct tangible benefits.