Book excerpt: This book introduces the use of Aggression Replacement Training as with juvenile gang members. It describes the use of ART in a multiyear project with a series of very aggressive juvenile gangs in New York City. Working with gangs as a unit, the goal was to not only teach them anger control and other skills but do so in such a way that their real-world reference group (the gang) was turned, as much as possible, into a prosocial rather than an antisocial support group. The book also providees an introduction to the history of gangs, current gang demographics, gang aggression and its etiology, and a review and critique of the various types of gang interventions that have been and are being tried.