Some form of delinquent activity is a common aspect of development for a majority of youth. For many, it appears to represent a time-delimited activity of adolescence that doesn't necessarily come to the attention of a formal system of social control (Moffit, 1993). However, a significant proportion of adolescents comes into contact with the justice system as a result of this behavior. In 1994, juvenile courts saw 1.75 million delinquency cases, with approximately 980,000 cases processed formally through a petition for an adjudicatory or waiver hearing (Stahl et al., 1999). For those adolescents who do come into contact with it, the justice system can represent a significant intervention in their lives (see Salekin and Fried and Reppucci, this volume, for a discussion of factors that contribute to juvenile violence).

The notion that adolescents are immature, have less decision-making capacity, and therefore should be treated differently than adults has permeated the juvenile justice system since its inception in 1899. Historical differences between the juvenile and adult criminal justice systems have been based on a fundamental notion about adolescent development and the appropriate societal response. In the criminal system, adults are presumed to be autonomous, competent persons who are able to make their own decisions about behavior and are held accountable for their choices. Because of their ongoing cognitive and social development, however, juveniles are considered less able to make competent decisions, and therefore are held less culpable and less accountable for their actions.