The paper examines the process of community integration and disintegration in two inner-city areas of post-socialist Warsaw and Tallinn which are undergoing a multi-layered social change. The main research problem pertains to the way in which social integration is moulded in transforming and, at the same time, socially diversifying urban areas. The districts under study are characterised by a process of social upgrading which brings inequalities to deprived but dynamically changing environs. The social structures identified evolve in the course of systemic transformation and increasing socio-economic diversification, the latter differentiating the old and new residents of the areas. The analysis looks for potential and actual factors underlying the emergence of new social networks and the persistence of those that were built in the pre-transformation period.