This is the 2007 version of an overview of urban change and a discussion of its main causes that IIED’s Human Settlements Group has been publishing since 1986. The first was Hardoy, Jorge E and David Satterthwaite (1986),“Urban change in the Third World; are recent trends a useful pointer to the urban future?”, Habitat International, Vol. 10, No. 3, pages 33–52. An updated version of this was published in chapter 8 of these authors’ 1989 book, Squatter Citizen (Earthscan, London). Further updates were published in 1996, 2003 and 2005–and this paper replaces the working paper entitled The Scale of Urban Change Worldwide 1950–2000 and its Underpinnings, published in 2005.

Part of the reason for this updated version is the new global dataset produced by the United Nations Population Division on urban populations and on the populations of the largest cities. Unless otherwise stated, the statistics for global, regional, national and city populations in this paper are drawn from United Nations (2006), World Urbanization Prospects: the 2005 Revision, United Nations Population Division, Department of Economic and Social Affairs, CD-ROM Edition–Data in digital form (POP/DB/WUP/Rev. 2005), United Nations, New York.