Citizenship is usually regarded as the exclusive domain of the state. However, changes to the structure of states resulting from decentralisation and globalisation have required a re-conceptualisation of citizenship, as authority is dispersed, identities multiply and political entitlements vary across territorial levels. Decentralisation has endowed regions with control over a wide range of areas relating to welfare entitlements, education and cultural integration that were once controlled by the state. This has created a new form of ‘regional citizenship’ based on rights, participation and membership at the regional level. The question of who does or does not belong to a region has become a highly politicised question. In particular, this article examines stateless nationalist and regionalist parties' (SNRPs) conceptions of citizenship and immigration. Given that citizenship marks a distinction between members and outsiders of a political community, immigration is a key tool for deciding who is allowed to become a citizen. Case study findings on Scotland, Quebec and Catalonia reveal that although SNRPs have advocated civic definitions of the region and welcome immigration as a tool to increase the regional population, some parties have also levied certain conditions on immigrants' full participation in the regional society and political life as a means to protect the minority culture of the region.