This begins by describing the work of the Pakistan NGO, Orangi Pilot Project-Research and Training Institute (OPP-RTI), in supporting improved provision for sanitation and other services in Orangi and other informal settlements in Karachi and in other cities and smaller urban centres in Pakistan. It then describes an OPP-RTI supported programme to map and survey informal settlements in Karachi and the Youth Training Programme that supported it. Some 9 million people live in katchi abadis (unauthorized settlements on government land), and another 15 million make their homes on informal sub-divisions of agricultural land on the urban periphery. Improving infrastructure and services and house-upgrading in these is hampered by a lack of maps, showing plot boundaries and existing infrastructure. Along with the mapping process itself, this had a number of important repercussions on policy issues related to infrastructure and the upgrading of informal settlements, planning concepts in local government and community-managed development work. Documenting these informal settlements demonstrated people’s involvement and investment in development in clear terms. As a result, planning agencies and local governments have realized the need to support this work, rather than ignoring or duplicating it.