Is nationality the only way of organizing political community? Given the ubiquity of the national principle, one might think so. But, in practice, the national principle is constantly challenged by what can be termed non-national identities. This article looks at manners in which such deviating identities can be conceptualized, how contemporary European states have attempted to deal with them when they arise and to what extent non-national modes of organizing political community can point towards a challenge to the national principle itself. In its capacity as an introduction to the special issue, this article seeks to frame the subsequent articles within the overarching theme of the tension between national and non-national communities in contemporary Europe.