People are usually born into their political communities, and only a minority of them become member of the given community by naturalisation. Sovereign states enjoy a great margin of appreciation in defining the rules of both birthright and acquired political membership. Most states employ some form of cultural affinity-based criteria relating to ethnic identity that differentiate between applicants that seek to acquire the nationality of the state. Indeed, such distinctions seem to be growing with the revival of ethnic and nationalist aspirations that Europe has witnessed for some years. We argue that human rights principles, first and foremost non-discrimination guarantees, should be taken seriously and effectively applied to these cases of naturalisation, and show what such a scrutiny entails. While the arguments presented here should apply more generally, special attention will be paid to events that primarily triggered the authors’ interest, the case of Hungary.