Data on 279 male heroin addicts admitted to methadone treatment clinics and interviewed six years after admission were collected from official police records, FBI rape sheet, Department of Motor Vehicles records, and methadone maintenance admission records. Urine samples were collected at the time of the interview in order to corroborate the interviewees' reports. The sample was 43 percent white and 57 percent Chicano; both groups had extensive drug and criminal histories. The first set of results deal with the costs of criminal justice intervention and treatment in controlling narcotics use and property crime. The findings indicate that while there was a marked increase in property crimes committed between the pre-addiction and addiction periods, the levels of drug use and property crime were low during the post-addiction phase. The average social costs per addict year were substantially lower during this post-addiction phase. According to the results, legal supervision alone only moderately reduces criminal and drug-using behavior; no long-term effects were observed after supervision was over. However, legal supervision combined with urine testing can impact the criminality of a population of heroin addicts. This study is one of the first to demonstrate the surveillance effects of criminal justice intervention on narcotics use and property crime rates among heroin addicts. Furthermore, the evidence suggests that legal supervision can be made more effective by requiring probationers and parolees to participate in drug treatment programs. However, in order to effect these results, coordination between the criminal justice system and drug treatment programs needs to be improved through policy development, assessments, interventions, and compliance monitoring. 5 tables, 1 figure, and 45 references.