The juvenile justice system consists of those agencies and institutions whose primary responsibility is to manage juvenile offenders. These juvenile offenders include delinquent youths and those children and youths judged to be incorrigible, truant, or runaway. The legal definitions of what constitutes juvenile delinquency are included in State juvenile codes and statutes, varying from State to State. Generally, a criminal law definition of juvenile delinquency holds that any person, usually under 18 years old, who commits an illegal act is considered a delinquent when he/she is processed through juvenile or family court. The second major type of juvenile delinquency consists of status offenses. These are behaviors that are not crimes if engaged in by an adult. Examples of juvenile status offenses are truancy, incorrigibility, curfew violations, and running away from home. The nine stages in delinquency case processing are as follows: Initial contact by law enforcement agencies; police informal handling, diversion, arrest, and/or referral to the juvenile court; court intake via the juvenile probation intake unit or the prosecutor's office; preadjudication juvenile detention; filing a delinquency petition in juvenile court or waiving to adult criminal court by the prosecutor; investigation or predisposition report prepared by a probation officer; juvenile court judge's adjudicatory decision and sanctions; participation and completion of mandated juvenile offender treatment program; and a juvenile aftercare plan. A discussion of the sources of juvenile delinquency official and unofficial statistics cites official police statistics, official statewide and national juvenile court statistics, self-report studies, and victimization studies. Based on statistics from these sources, this chapter reports that juvenile delinquency and victimization rates have apparently stabilized during the current decade; however, millions of adolescents continue to become involved in juvenile delinquency each year, manifesting a complex and difficult social problem with no easy solutions. 7 tables, 6 figures, and 51 references