The review discusses the monograph “Šiaurės rytų aukštaičiai vilniškiai: ribos ir diferenciacija” [North-Eastern Aukštaitian Vilnius Ethnic Region: Boundaries and Differentiation] by Vytautas Kardelis (2009). The author chooses two specific objectives: to discuss the boundaries of the north-eastern Vilnius ethnic region and analyse internal differentiation. Instead of traditional, or atomistic, classification, the monograph establishes differentiation of the north-eastern Vilnius ethnic region based on the principles of structural dialectology. The classification of Kardelis refers to the paradigm identification of phonemes and the research of vocalism system. Based on the principles of structural dialectology and Girdenis’ phonology school, the boundary between north-eastern and south-eastern Vilnius regions is delineated: Ignalina district, south-western Švenčionys and eastern Švenčionėliai regions are attributed to the north-eastern Vilnius region, whereas the localities southwards from Švenčionys, i.e. Strūnaitis, Petruškos, Šutai, are attributed to the south-eastern Vilnius region. According to the reviewer, some phonetic interpretations could have been reasoned in greater detail. A separate chapter comprehensively describes the contextual and structural neutralisations, consistently keeping to the principle of dynamic synchrony. The researcher encounters a problem: what should be considered a systematic phenomenon and what should be ascribed to the influence of the standard language or borrowings, i.e. the periphery of subdialect? However, some phenomena are inconsistent in the speech of the same informant. In such case, the author includes both in the system as equal facultative – competing – variants
