Prior studies of juvenile drug courts have been constrained by small samples, inadequate comparison groups, or limited outcome measures. The authors report on a 3-year evaluation that examines the impact of juvenile drug court participation on recidivism and drug use. A quasi-experimental design is used to compare juveniles assigned to drug court with those assigned to standard probation in Maricopa County, Arizona. Findings indicate drug court participants were less likely to recidivate than youths in the comparison group. Analyses of drug use show no significant difference between groups in marijuana use but reveal that drug court participants were more likely than juveniles in the comparison group to test positive for cocaine. Family stability, school attendance, and legal indicators were important predictors of drug court effectiveness. Last, findings indicate the majority of juveniles in drug court were unsuccessful in meeting program requirements and subsequently released to state-operated facilities or standard probation. (Contains 5 tables and 7 notes.)