ONE BILLION people now live without adequate shelter, water and sanitation, and UN-HABITAT estimates that the number of slum dwellers grows by 70 million per year. The problems that go along with slums – poor health, environmental degradation, poor nutrition and safety issues – present enormous challenges to governments in developing countries, where the problem is the greatest.

The UN estimates that the resources required to achieve the Millennium Development Goal improving the lives of 100 million slum dwellers by 2015, are USD 20 billion per year. This is far above the current level of investment going into slum upgrading and prevention. The financial resources required to fully address the needs of one billion slum dwellers are estimated by Rockefeller Foundation to be between USD 1 and 2 trillion. There is simply not enough money available through governments and donors to begin to address social and affordable housing needs at the scale required.