Access to affordable housing in the Global South is very limited for millions. Many households have chosen incremental self-construction; herewith sustainability does not have the highest priority. The main question is whether affordable housing for the urban poor and the need for sustainable housing and urban development can be combined. Transference of knowledge to (self) builders is a key issue, as is the role of assistance in self-help housing. It is argued in this paper that sustainable goals for low-cost housing and applications are achievable. Measures concerning the physical development of neighbourhoods, such as urban density and connectivity are equally as important as measures concerning community development. The latter include support for community-based organizations, small housing cooperatives (or similar forms of cooperation) and individual households or small groups that build and improve their houses incrementally. Adequate planning and social organization and cooperation are preconditions for achieving sustainability in incremental housing.