Understood as a mass siege of an established government by its own population with the goals of bringing about regime-change and effecting substantive political or social change, revolutions are, in Foucauldian terms, exceptional moments of “chance reversal”--when the ongoing trajectory of a political order is ruptured and potentially altered in fundamental ways by those subject to it.  But the ways in which populations go about the business of regime-change from below, the reasons they engage in such action, and the social forces that mobilize in revolution have altered dramatically over the past century.   This book is about that transformation--and in particular, about the impact of urbanization and the concentration of people, power, and wealth in cities on the incidence, practice, and consequences of political revolutions.