This study examines the impact drug abuse treatment has on the subsequent criminal behavior of opiate users. Based on extensive data from an automated management information system of all the Orange County California Drug Abuse Services and all of the State of California Bureau of Criminal Statistics' Arrest and Citation and Offender-Based Transaction files for the years 1975 through 1978, this research utilizes a computer records matching program to identify drug abuse clients amount of official criminal activity throughout California. The program produces statistical matches without using any complete identifiers (e.g., last name), thus anonymity is assured and the protection of the confidentiality of clients. One significance of the study is that it integrates all treatment and criminal justice information. It is estimated by the treatment system's administration that 4,000 opiate using clients have been processed during the proposed study period, and roughly 2,000 of these have been on methadone maintenance. The research includes adequate comparisons including the criminal and the general population of Orange county. Relative crime rates will be generated for all these population components and Census data will be used to estimate the general population for the study years. The analysis will include the following comparisons: (1) between groups; (2) within groups; (3) between treatment populations. The first involves the comparisons between the general population, the offender population and treated drug abusers. The second utilizes an offender-based transaction system and concentrates on the comparisons between types of offenders, and their dispositions within the criminal justice system on the basis of the addict-non-addict distinction; the third comparison is within the treatment system in terms of the impact of programs.