This introductory article to the Special Issue Marshall in Brussels? A new perspective on social citizenship and the European Union first argues that there is a need for a novel systematic framework that captures the increasingly complex web of relationships between the European level and the national and local levels in the creation and implementation of social rights. It then summarizes the contributions of the articles included in the Special Issue, starting with the first article that provides such a novel framework, a power resource-based and multi-layered conception of social rights which looks at social rights as bundles of three key power resources: normative, enforcement and instrumental resources. It then shows how the other articles apply this framework when analysing a variety of issues related to European social citizenship. Finally, it sums up the main contributions of the Special Issue: its contribution to the further development of power resource theory; to the theory of social citizenship; and to capturing how social rights in the EU increasingly result from the creative assemblage of different resources provided by different actors and levels of government, resulting in a ‘marble cake’ pattern akin to that existing in historical federations like the US or Switzerland.