US-based journalist Robert Neuwirth spent two years visiting in informal settlements across the globe, including Kibera (a slum in Nairobi, Kenya), Rocinha (a favela in Rio de Janeiro, Brazil), a gecekondu bölgesi zone in Sultanbeyli, Istanbul, Turkey and Dharavi and Sanjay Gandhi Nagar (two squatted areas in Mumbai, India).

[2] He also gives a partial history of slums in such places as London, New York and Paris, suggesting that informal settlements are an integral part of urbanization and concluding on an optimistic note that there are so many squatters that their needs cannot be ignored.

Writing in Forum Qualitative Social Research, Brian Christens said the book was "rich with insights" whilst also criticising Neuwirth's methodology.

In Environment & Urbanization he takes exception to Neuwirth's dismissal of the National Slum Dwellers Federation in Mumbai as "'feel-good' organizing", arguing that the federation, allied with groups such as SPARC and Mahila Milan, provides a concrete means for slum dwellers to better their conditions.

[5] In Harvard Design Magazine, John Beardsley commented what the "book lacks in trenchant social analysis or substantive policy understanding it more than makes up for in a close reading of what life is like in four settlements around the world".