Thus far the study has involved 2 years of study of a large sample of youth already involved with the justice system. One finding at this stage is confirmation of the strong link between drug and alcohol use and various indicators of delinquency, including official arrests and levels of self-reported offending. Further, the data show that substance abuse treatment works in both reducing substance use and related offenses. Such treatment was found to be most effective when conducted in detention centers and training schools. Another study finding is that the youth who do the most offending do not spend the most time in institutional care. All youth who commit delinquent acts tend to be sanctioned similarly. Thus far there is no evidence of attitudinal change among youth, suggesting that adolescent attitudes that underlie delinquency do not change significantly over the short term. The study sample was recruited from among juvenile offenders being processed in two large urban court systems, Philadelphia, PA, and Phoenix, AZ. To be eligible for inclusion in the sample, a youth must have been adjudicated or transferred to criminal court for a felony, a misdemeanor weapons offense, or a misdemeanor sexual assault committed between the ages of 14 and 17. Between 2000 and early 2003, 1,355 youth--701 in Philadelphia and 654 in Phoenix--were enrolled in the study. Data on the youth were obtained primarily through interviews with them. To date, over 14,000 interviews have been conducted, involving approximately 31,000 interview hours. 13 notes