This article deals with the issue of sub-state citizenship in the post-Yugoslav countries and focuses on the emergence and definitions of membership. The article analyses conceptions of nationhood and territorial compositions of the states, proceeds with the analysis of sub-state entities' governance arrangements and compares conceptions of nationhood and membership in state-wide and sub-state polities. The article identifies four broad categories of sub-state polities and two diverging tendencies in the definition of membership. At one end of the spectrum, there are cases in which membership in regional polities is based on territorial, multi-ethnic and civic principles. At the other end, membership is defined in ethno-national terms.