One of the specific features of many post-Soviet cities is their multiethnic structure, which was strongly influenced by internal migrations within the Soviet Union. Political and economic reforms in the 1990s led to changes in ethnic composition, and the attention given to the processes of ethnic-segregation has started to increase. While most studies focus on capital cities, much less is known about second-tier cities. This article examines the interrelationships between ethnic and social segregation in the metropolitan areas of Lithuania (Vilnius, Kaunas, Klaipėda). The authors use Lithuanian census data from the years 2001 and 2011 to obtain insight into the recent changes in the socio-spatial differentiation of the largest ethnic groups: Lithuanians, Poles, and Russians. The results show a clear relationship between the socioeconomic and ethnic status of the residents of metropolitan areas and, therefore, suggest that ethnic segregation is strongly linked to the general processes of social segregation. The findings also show that the larger the proportion of a certain ethnic minority group in an area, the larger the proportion of lower (social) status residents in this group. In addition, in such cases, ethnic minorities often tend to concentrate in particular areas within the cities.