This case study covers two peculiar aspects of horizontal governance coordination: governance across nation-state borders as well as inclusion of national minorities residing in border regions, with ethnic, linguistic, and cultural connections to the neighbouring country—their kin-state. Here, we investigate two regions in Europe, which are very diverse in landscape, economic development, and governance structures, but similar in that they are a product of national conflict, resulting in ethno-national diversity organised in non-territorial autonomy for national minorities: Sønderjylland-Schleswig, crossing the Danish-German land border, as well as the Bihor-Hajdu-Bihar Euroregion crossing the Hungarian-Romanian border. National minorities pose challenges to governance, but also opportunities. In border regions and regional cross-border governance, minorities can overcome barriers in terms of language, culture, or even administration. Therefore, we argue that national minorities should be involved in horizontal governance coordination.