THE REDUCTION OF CRIMINAL ACTIVITY IS DIFFICULT TO LINK WITH METHADONE TREATMENT PER SE, ALTHOUGH REFERRALS FROM THE CRIMINAL JUSTICE SYSTEM TO DRUG TREATMENT PROGRAMS CONTINUE, WITH THE EXPECTATION THAT REHABILITATION WILL OCCUR. THIS STUDY EVALUATES PATIENTS IN TWO METHADONE MAINTENANCE (MMP) AND ONE METHADONE DETOXIFICATION (MDP) PROGRAM AT THE CENTER FOR ADDICTION SERVICES, CRIMINAL BREAKTHROUGH MAINTENANCE PROGRAM, PUGET SOUND SOCIAL PROGRAMS, INC., WITH EMPHASIS ON THEIR CRIMINAL HISTORIES PRIOR, DURING, AND AFTER TREATMENT. THE SAMPLE INCLUDED 130 MAINTENANCE CLIENTS AND 62 WHO HAD RECEIVED DETOXIFICATION. DEMOGRAPHIC, SOCIOLOGICAL, AND CRIMINAL HISTORY VARIABLES WERE TESTED FOR THEIR ABILITY TO ACCOUNT FOR CHANGES IN ARREST PATTERNS OVER PERIODS OF TIME AVERAGING 2 YEARS (PRETREATMENT) AND 2 YEARS (POSTTREATMENT). WHILE THE NUMBER OF ARRESTS DECLINED AFTER ENTERING TREATMENT, CERTAIN GROUPS REMAINED AT HIGH RISK OF ARREST AND/OR CONVICTION. PATTERNS OF CRIME AS MEASURED BY OFFICIAL ARREST STATISTICS DO NOT APPEAR STABLE OVER THE STUDY PERIODS FOR THE TREATMENT SAMPLES. FINDINGS ALSO INDICATE THAT A LARGE PROPORTION OF TREATED ADDICTS WERE AND CONTINUED TO BE INVOLVED IN CRIME BEFORE, DURING, AND AFTER TREATMENT. DATA SEEMS TO INDICATE A SLIGHT DIFFERENCE IN THE PATTERN OF CRIMINALITY BETWEEN THOSE ADDICTS TREATED BY MEANS OF DETOXIFICATION VERSUS THOSE TREATED BY MAINTENANCE, IMPLYING DIFFERING CLINICAL POPULATIONS. THUS, THE STUDY SUPPORTS THE GENERAL FINDING THAT CHANGES IN DRUG USE WHILE IN METHADONE TREATMENT MAY BE PARALLELED BY CHANGES IN OVERALL NUMBERS OF ARRESTS AND RELATED CRIMINAL ACTIVITIES FOR BOTH ADDICT GROUPS. A LIST OF REFERENCES IS APPENDED. (AUTHOR ABSTRACT MODIFIED--LGR)