Book excerpt: For the first time in history, the majority of the world's population lives in cities, the result of a rapid process of urbanization that started in the second half of the twentieth century. 'Megacities' around the world are rapidly becoming the scene for deprivation, especially in the global South, and the urban excluded face the brunt of what in many cases seems like low-intensity warfare. Featuring case studies from across the globe, including Latin America, the Middle East and Africa, Megacities examines recent worldwide trends in poverty and social exclusion, urban violence and politics, and links these to the challenges faced by policy-makers and practitioners.