ABSTRACT: Designed as social space according to CIAM principles in the second half of the 20th century, the open public space in the large housing estates in the periphery of Sofia was transformed for the recent 30 years due to the changing socio-economic, political, and cultural conditions. The broad open spaces have been adapting to the arising societal demands, changing lifestyles and mixed uses by accommodating competing or complementary uses, generating new activities or “waiting” update or re-design. The paper discusses the potential of integrating social dimensions and physical characteristics for sustainable management of open public space in large housing estates. Based on a case study approach developed within on-going research project, the paper summarizes the results from the set of conducted qualitative and quantitative methods, spatial analyses, and participatory activities in the URBiNAT Living Lab in Nadezhda district, Sofia. Urban open space is analysed as territorial asset and through the social practices thus revealing the complexity of overlapping roles, users, and audiences. The perceptions, attitudes, dreams, and aspirations towards public space as well as the motivations and liability to participate are studied from the perspective of pupils, citizens and district administration staff. The research findings outline the need for reinventing urban policy by integrating the right-based approach into all phases of public space lifecycle management, (re)considering traditional property and ownership paradigms, building new frameworks for participation and meeting local institutional efforts and bottom-up movements, establishing dialogue with diversity of actors, and providing flexible design that enables multiple interpretations and uses.