In the process of developing into a modern nation, the Slovenes were confronted with a problem that indeed plagued many European peoples: a dual designation for a single people and its language: the ethnonyms Slovenci and Kranjci (‘Slovenes’ and ‘Carniolans’) and the linguonyms slovenski and kranjski (‘Slovene’ and ‘Carniolan’). There are several indications that, as early as the sixteenth century, the term ‘Carniolan’ served not only as the designation for the inhabitants of Carniola but also an ethnonym. During the Protestant period, it already spread beyond the Carniolan provincial borders and came on a par with the ethnonym ‘Slovene’. The Slovenes in Carniola (thenceforth only) self-identified with the designation ‘Carniolans’, whereas outside its borders, they variably, from one province to another, identified themselves either as Slovenes or Carniolans, sometimes alternating between the two designations. Later on, the linguonym ‘Carniolan’ also established itself to replace the linguonym ‘Slovene’. The question whether the nominal Carniolization during the ethnogenesis of the Slovenes had a disintegrating effect, may be answered both affirmatively and negatively.