The making of Europe is an ongoing process, and this concerns the emergence of new states with new constellations of majorities and minorities, changes of demographic patterns caused by internal European migrations and demographic influx from outside Europe, changes of the political status of ethnic groups and their languages. Language-related boundary-marking of ethnic identity occupies a pivotal role in these processes, producing various scenarios of contact and conflict between ethnic groups throughout Europe. In order to perceive the magnitude of this phenomenon it is necessary to inspect the infrastructure of the complex concept “ethnicity” and to shed light on how ethnic processes have been conceptualized in the history of European reasoning.