The analysis focused on the demographic and offense characteristics of the juveniles receiving services, their experience with drug abuse and prior drug treatment, screening for drugs after being placed in JIP, the accuracy of probation officers' subjective assessments of the youths' drug use, and background factors relating to short-term successful outcomes. Results revealed that these juveniles did not abstain completely from the use of marijuana and cocaine, because 28 percent tested positive for marijuana and 7 percent tested positive for cocaine at least once while under supervision. However, probation officers' estimates of prior drug use were clearly related to subsequent drug use, because only a small percentage of the youths considered nonusers of marijuana and cocaine in the year before intervention actually tested positive for the same drug while under supervision. Tables, 17 references, and appended forms from the program