As a result of rapid proliferation of urbanization, there is an insufficient supply of green spaces in dense urban city while the population and living density are both very high. This insufficiency associates with a number of problems on both individual and community. Communal sky garden (CSG) thus turns into an alternative solution as a co-existence between building and vegetation within the same plot of land for the enjoyment of the occupants of the respective development. This study aims at examining the design elements which affect the social performance of CSG for high rise buildings in dense city. There are totally 25 number of residential developments which have the provision of CSG since the issuance of Joint Practice Note No.1 and No.2 in 2001. Eight of them have been selected for the Study. The sky garden design of these developments has been examined and analyzed from different perspectives which include building controls, on-site measurements and observations, questionnaire survey and interviews. Views from public, developers and design professional have also been collected to generate a holistic review on such provision. Several features which are unique to CSG has been identified. The most apparent one is the provision couples with the refuge floor while the layout is dictated by the typical floor plate. It thus imposes limitations on the design and the schedule of accommodations. Also, based on the design layout and characteristics, the eight selected ases have been classified and categorized into four CSG typologies, namely (i) typical type; (ii) linked-up type; (iii) duplex type; and (iv) balcony type. These typologies facilitate the review and analysis of the current provision of CSG. The findings from fieldworks have exhibited that people’s perception on CSG is positive. Its provision is highly supported and appreciated nevertheless of their infrequent use rate. When designing CSG, the considerations are slightly different from those designed at street or ground floor level. Greening is still considered as important which has been validated in the current Study; open views from CSG and its tranquil environment which are unique to the provision constitute the primary concerns of users when consider visiting the garden. These conditions offer an alternative space for residents of the respective development to relax and relieve stress. However, the role of CSG cannot be overemphasized; it, in fact, is complementary to the open space system by providing a garden at “doorstep” for residents particularly for those developments lacking competing facilities such as podium garden and nearby open space. Hence, the provision is not only environmentally sustainable, but also socially sustainable in terms of improving physical health and well-being of residents and their quality of life. This Study also offers a significant reference for the comprehensive design and in-depth understanding on the value and role of CSG in the built environment especially for high rise residential buildings in dense city. The collected findings and the deliverables provide a good reference in future CSG provision in Hong Kong. / published_or_final_version / Architecture / Doctoral / Doctor of Philosophy