The research sought to determine the possibility of distinguishing the persons for which methadone maintenance is more likely to be successful. The analysis focused on the information that the treatment program routinely collected on the participants' demographic characteristics, family relationships, drug abuse and drug treatment history, physical and mental health, and length of methadone treatment. Results document how CS Networks can help simulate the consequences of alternative treatments on the basis of data usually collected by treatment centers for their client files. Findings also demonstrated how this technology can support treatment personnel and thereby improve the quality and timeliness of the necessary interventions with the persons being treated. Findings also indicated that during treatment planning the networks can support the matching of the addict and the treatment. Further research on this approach should analyze data files from persons in treatment in different centers and should cover many years. Figures, tables, appended tables and list of variables, author biographies and photograph, and 5 references (Author abstract modified)