Most research on EU citizens’ social rights has focused on legally defined rights, largely ignoring substantive social rights. This paper concentrates on the particular combination of formal rights and substantive entitlements that is constitutive of European social citizenship. The paper makes two points. First, perhaps paradoxically, supranational social citizenship raises the significance of the local level of the welfare state. Because citizens who move within an economically diverse Union often lack formal and substantive social rights, and because measures targeting the poor and those in acute need are still municipal responsibilities, local welfare provision and its boundaries are made salient and significant for EU citizens’ substantive rights. Second, drawing on empirical material collected through interviews with stakeholders in Berlin, Hamburg, Gothenburg and Stockholm, the paper argues that local actors’ responses to locally experienced consequences of freedom of movement and limited social rights shape EU citizens’ substantive social rights, exerting a bottom-up effect on European social citizenship.