The state of the art in research on residential segregation and concentr= ion in Central and Eastern Europe (CEE) largely focuses on process descri= ion (e.g., the multitude of works on gentrification and suburbanization).= ven though major advances in the conceptualization and measurement of seg= gation have been made, works that scrutinize the patterns of segregation = d/or concentration in CEE are rare, while studies that simultaneously exp= re and link segregation patterns under socialism and after are virtually = nexistent. Relying on Polish census-tract level data on the educational s= ucture of population in 1978, 1988, and 2002, this study explores the pat= rns of social segregation and concentration in the three major Polish cit= s (Warsaw, Cracow, and od), representing different paths of development u= er socialism and after. The results show that the population of the three= ajor Polish cities was still socially heterogeneous at the census tract l= el in 2002. ! he results also reveal that the level of social residential segregation i= the three cities has been decreasing steadily since 1978, irrespective of= he prevailing economic system.