A review of current knowledge about street gangs concludes that most of it consists of unverified theoretical propositions. Evaluation information on gang prevention programs indicates that these programs have either been mildly effective, ineffective, or even contributory to gang delinquency. A review of what is known about gangs concludes that they come in a variety of forms, and delinquency and violence can emanate from any gang; however, gangs that have existed for a number of years are the logical targets for intervention. Factors that increase gang cohesiveness are likely to lead to increased gang recruitment and delinquency. The second major part of the book focuses on observations about gang programs and street workers who target gangs. The discussion notes that street workers are handicapped by the absence of sufficient knowledge of street gangs and effective intervention strategies. Street workers must, therefore, act as pioneers and devise intervention strategies that seem appropriate for the gangs and gang members with whom they are dealing. Various worker styles and activities are described and assessed. A primary need is for police administrators and social work administrators to cooperate in assessing the information on gangs in their jurisdiction and in developing strategies that complement one another. The concluding section of the book describes and assesses a gang intervention program that tested a major hypothesis concerning the relationship between gang cohesiveness and delinquent behavior. Chapter references, appended supplementary data, and a subject index