Government projects to assist the poor in self-building have been common since the mid twentieth century.6 In Nigeria, for example, the colonial government acquired large tracts of land and laid out and installed basic infrastructure before allocating the serviced plots to individuals and corporate bodies for development.7 In the mid-1940s, the government of Mexico authorized private developers to lay out vast residential housing estates (without imposing planning requirements and development controls) and sold plots at costs affordable to very low-income households. For example, Ciudad Netzahuacoyotl, on the outskirts of Mexico City, was developed in 1958 with minimal services, had a population of over half a million by the 1970s, and is now fully developed with a population of over 2 million.

Early state-supported incremental housing initiatives tended to be piecemeal, one-off projects. Official programmes for the construction of subsidized completed housing dominated public housing policies. At the same time, urban squatter settlements and slums grew rapidly on illegally invaded and subdivided land, but those highly visible, informal, and incremental processes were in no way seen as a legitimate means to provide housing. It was only in the 1960s that this view began to change. Largely due to the research and writings of a small group of academics, the incremental approach began to be recognized as a logical and effective strategy employed by the poor to house themselves.

Notably, John F. C. Turner9 and William Mangin10 looked at and analyzed the highly organized and effective informal urban housing strategies of poor people in Peru. Charles Abrams also recognized the effectiveness of informal housing processes and suggested state support for incremental housing projects as early as 1964.11 Encouraging and supporting the poor’s approaches to meeting their own housing needs began to be recognized as a way forward for policy makers, who were struggling to build sufficient public housing units at affordable prices to shelter rapidly growing low-income urban populations.