The ‘European social dimension’ offers a strategic entry point for analysing the development of citizenship in the European Union (EU). The first part of this contribution discusses the functions of social citizenship in this emerging multi-level governance network. Second, the analysis deals with two prominent and stylized paradigms that have sought to grasp the new multiple-level quality of social citizenship in the EU: residual and post-national concepts of membership in liberal democracies and advanced welfare states. Although each of these approaches captures selected elements of social citizenship, they are unable to deal with rights and duties in multiple governance levels in a satisfactory way. Therefore, the discussion moves to an alternative concept–nested citizenship. This means that European citizenship is nested in various sites: regional, state and supra-state forms of citizenship function in complementary ways–while the associated norms, rules and institutions are subject to constant revision and further development on all governance levels. Third, the analysis shows that the concept of nested citizenship can help to overcome the fruitless dichotomy of Euro-optimism and Euro-pessimism concerning social policy and citizenship. This discussion suggests a conception of European social citizenship as a common project, evolving towards common present- and future-oriented understandings of substantial rights and democratic principles in the EU.