American popular culture has built up a strong mythology about street gangs and their members. Some of it is fueled by movie and song – from the lyrics of Bernstein and Sondheim's classic Broadway hit to the grittier depiction of gang life in contemporary gangsta rap and Spike Lee movies. Some of it is fueled by the coverage of gangs in the mass media; some of it by autobiographies like Claude Brown's Manchild in the Promised Land (1976) and Sanyika Shakur's Monster (1998). Whatever the source, these images are entertaining and have taken firm root in popular views of gangs and gang members; their accuracy is another matter entirely.

Indeed, at one and the same time, they glorify and demonize gang members, presenting a warped picture that misses the mark in fundamental ways. For example, the idea that gang life is permanent, reflected in the lyrics that opened this book, is dead wrong. Gang membership, for the vast majority of gang members in America, turns out to be a rather fleeting, transient adolescent dalliance. It is the job of science to correct the record, to describe the phenomenon as accurately as possible, to attempt to explain why it happens, and to propose an appropriate response. This book is one contribution to this long-term effort.

It differs somewhat from previous approaches to this topic.