This knowledge overview on social sustainability from an urban planning perspective has been developed as a result of a Mistra Urban Futues project. The project gathered a large number of actors from research and practice, from local and regional level, as well as from both small and large municipalities. All actors had a common desire to create a greater understanding of what social sustainability might mean in relation to urban planning. The ambition is that the resulting report will help researchers to gain a better understanding of the practical challenges and needs regarding social sustainability. Also, that practitioners get a wider theoretical reference framework that they can use as a basis for their work. In the report it is concluded that social sustainability in urban planning has different meanings in different contexts. A number of approaches on social sustainability in relation to urban planning are presented, to provide guidance and urge for reflection. The report also illustrates how social planning can contribute to (and hinder) social sustainability in different ways. It is emphasized that social sustainability is not a static state that can be achieved once and for all, but rather an ongoing process in which urban planning can play an important role. The report also provides a number of interesting examples of how actors within the framework of Swedish urban planning can address issues of social sustainability. Finally, a number of identified knowledge gaps are highlighted, as guidance for continued development work and research initiatives.