The establishment of drug courts has been one of the most popular criminal justice responses to drug crimes in recent years. Juvenile drug courts have also sprung up and have become widespread, with over 140 juvenile drug courts nationwide and more scheduled for implementation. According to the authors, only three published studies to date have examined the impact of juvenile drug courts on subsequent delinquency. These studies have indicated that juvenile drug courts show promise in reducing substance use and delinquency, however, these early studies were constrained by small sample sizes, inadequate comparison groups, or limited outcome measures. As such, the current study involved a 3-year evaluation (October 1997 to November 2000) of the impact of drug court participation on measures of recidivism and delinquency in Maricopa County, AZ. The authors employed a quasi-experimental design to compare 114 juveniles assigned to drug court with a comparison group of 204 juveniles assigned to standard probation. Four hypotheses were tested: (1) youths in drug court will have lower recidivism rates than youths on standard probation; (2) youths with more serious criminal histories will be more likely to recidivate than less delinquent youths; (3) youths enrolled in school and who have fewer guardianship changes will have lower recidivism rates; and (4) juveniles who spend more time in drug court will have lower recidivism rates than juveniles who spend less time in drug court treatment. Drug use measured cocaine and marijuana use. Results of logistic regression analysis indicated that drug court participants were less likely to recidivate than their standard probation counterparts. As for drug use, no differences were found between the groups with regard to marijuana use, however drug court participants were more likely to test positive for cocaine use than their standard probation counterparts. Three main variables were found to predict drug court effectiveness: family stability, school attendance, and legal indicators. Findings also revealed that the majority of drug court participants did not meet program requirements and were released to State-operated facilities or to standard probation. Future studies should utilize program release data rather than simply program completion in order to test the effectiveness of juvenile drug courts. Tables, notes, references, appendix