In this brief, accessible text, Malcolm Klein presents insights gained from his forty years of experience investigating street gangs. In Part I he reveals some of the dominant trends that have emerged over the course of his research, defining and describing gangs, their locations, who joins them, and the types of illegal behavior in which they engage. In Part II he delves into the conceptual contexts that help us to understand those trends, examining gangs in relation to other small groups, comparing gangs in the U.S. to those in Europe, and discussing approaches to gang control. About the Series Keynotes in Criminology and Criminal Justice provides essential knowledge on important contemporary matters of crime, law, and justice to a broad audience of readers. Volumes are written by leading scholars in that area. Concise, accessible, and affordable, these texts are designed to serve either as primers around which courses can be built or as supplemental books for a variety of courses.