Although social objectives are frequently part of the pursuit of sustainable urban development, how such social sustainability goals can be achieved in urban development practices remains a largely unsolved puzzle. While scholars increasingly acknowledge that urban social sustainability is a plural concept that needs to be specified in different situations, thus far very few social sustainability studies have focused on the processes in which such specifications take place – i.e., the implementation processes in which policies are brought into practice in urban areas or neighborhoods. This dissertation develops an understanding of how institutionalized governance processes affect the implementation of policy goals related to social sustainability in area-based urban development projects. The research draws on Sen’s Capability Approach (CA) to construct a capability-centered evaluation of such efforts. More than other normative approaches that primarily focus on the distribution or quality of spatial goods, the principles of the CA focus on the fact that different people have different experiences. Unique personal, social, and environmental circumstances per individual imply that people have different capabilities: the actual freedoms to do or be what one considers valuable for a dignified life. A promising role is reserved for the CA to investigate how exactly the diversity of human beings can be incorporated into urban development and planning processes. This provides a sincere response to the calls of social sustainability scholars that more ‘human-centered’ approaches are needed. The dissertation hypothesizes that governance processes around urban development projects hold various elements that affect the implementation of social sustainability in contemporary cities, and subsequently, influence whether ‘capability-centered urban outcomes’ are achieved or not. In that way, this dissertation analyzes how governance processes in urban development practice relate to capability-centered evaluations of urban social sustainability outcomes. Whereas these two aspects are often investigated separately – i.e., studies often either focus on analyzing the mechanisms within governance processes or on describing and evaluating social outcomes in the urban environment – this dissertation explicitly brings these together. The governance process is investigated from a collaborative governance perspective to analyze which activities and interactions between the different stakeholders affect capability-centered social sustainability outcomes in urban environments, and complementary, from an institutionalist perspective that explores what less-visible, yet structural elements of governance condition the emergence of capability-centered governance activities.