Book excerpt: Are there any commonalities between such phenomena as soccer hooliganism, sabotage by peasants of landlords' property, incidents of road rage, and even the events of September 11? With striking historical scope and command of the literature of many disciplines, this book, first published in 2003, seeks the common causes of these events in collective violence. In collective violence, social interaction immediately inflicts physical damage, involves at least two perpetrators of damage, and results in part from coordination among the persons who perform the damaging acts. Professor Tilly argues that collective violence is complicated, changeable, and unpredictable in some regards, yet that it also results from similar causes variously combined in different times and places. Pinpointing the causes, combinations, and settings helps to explain collective violence and its variations, and also helps to identify the best ways to mitigate violence and create democracies with a minimum of damage to persons and property.