The paper deals in detail with previously understudied types of language contact settings in the Balkans (Southeastern Europe), which present a continuum between ethnic and linguistic separation and symbiosis among groups of people. The presentation achieves several aims: it critically assesses the Balkan Sprachbund theory; it analyses general contact theories against the background of new, original, representative field data; it employs and contributes to recent methods of research on linguistic convergence in bilingual societies; it proposes new general assessments of extra- and intralinguistic factors of Balkanization over the centuries; it outlines prospects for future research. The factors relevant for contact scenarios and linguistic change in the Balkans are identified and typologized through models such as those related to a balanced or unbalanced (socio)linguistic situation. The core part of the paper examines in linguistic terms (i. e., it provides syntheses and analyses of new experimentally confirmed and existing knowledge) the dialects (idioms) of multiethnic, multilingual groups of people. The focus is on the idioms of bi- and multilingual speakers in Golo Brdo, Mrkovići, Prespa, Carașova and Himara, grouped in different contact settings with one another. The major levels of language structure (phonetics/phonology, grammar, lexicology and text, including the verbalization of traditional culture) are taken into consideration in order to analyze the cases considered from the point of view of linguistic contactology, and to speculate about the instructiveness of these cases for the Balkan linguistics in general.