This study examines the extent to which the transfer of legislative competence to polities above and below the state problematizes a national model of membership. The study first examines fragmentation of competences determinative of social membership across the polities of two ‘asymmetric constitutions’ (constitutional structures in which both the whole and the parts are distinct territorially-bounded political communities, and in which legislative competence is allocated unevenly across the constituent polities). Two case studies then explore how those polities exercise those competences so as to define the boundaries of equal social membership, and how these boundaries interact across the constitutional structure. The study highlights three observations in support of its conclusion that constitutional asymmetry presents a challenge to a national model of membership: constituent polities of the asymmetries under examination allocate social rights primarily by reference to residence, thus lending (qualified) support to transnational and a-national theories of membership; differentiated social rights enjoyed by a particular sub-set of nationals are incompatible with the presumed equality of nationals under a national model of membership, resulting in the perception of inequity and discrimination; and the interdependence of membership competences across the constitutional asymmetry means that it is no longer possible for a polity to exclusively determine the boundaries of social membership.