The philosophy underlying the juvenile justice system and its actual operation are examined. Official and self-report data on juvenile offending are presented, and characteristics of juvenile offenders are delineated. Three studies test models derived from social control, differential association, and labeling theories of juvenile delinquency. An ethnological study of violence in a Dutch youth club considers the experiences of victims, witnesses, and aggressors in violent behaviors. Factors contributing to police decisions regarding the disposition of juvenile cases also are examined with reference to the effects of philosophy underlying police work, information gathering, and police assistance to juveniles in three juvenile investigation units. Possible effects of official police or prosecutor interventions on juveniles' subsequent delinquent behavior, renewed contacts with the juvenile justice system, and level of social integration also are examined. Finally, an experimental program emphasizing alternative work and/or training sanctions for juvenile offenders is described, and results of a preliminary evaluation are presented. Chapter figures, tables, and references. See NCJ-114383 to NCJ-114392 for individual papers.