OVERALL DECLINES IN ARRESTS WERE FOUND OVER A 3-YEAR FOLLOWUP PERIOD FOR 473 DRUG ADDICTS TREATED BETWEEN OCTOBER 1969 AND JUNE 1971 AT THE ADDICTION RESEARCH AND TREATMENT CORPORATION (ARTC) PROGRAMS IN BROOKLYN, AND OVER A 2-YEAR PERIOD FOR 271 PATIENTS WHO ENTERED THE SANTA CLARA COUNTY METHADONE TREATMENT AND REHABILITATION PROGRAM BETWEEN OCTOBER 1969 AND JULY 1970. FOR BOTH GROUPS OF PATIENTS, ASSAULT ARRESTS SHOWED LESS OF A DECLINE THAN DID OTHER TYPES OF ARRESTS. COMPARED TO CALIFORNIA PATIENTS, BROOKLYN PATIENTS WERE ARRESTED LESS FREQUENTLY BUT FOR MORE SEVERE OFFENSES AT ALL POINTS IN THE STUDY (PRIOR TO AND DURING ADDICTION, AND AFTER ENTERING TREATMENT). AT THE ARTC FACILITY, DECREASED CRIMINAL ACTIVITY WAS SIGNIFICANTLY RELATED TO A RELATIVELY GOOD PRETREATMENT DRUG HISTORY AND TO DECREASED DRUG USE DURING PROGRAM PARTICIPATION. OUTCOMES WERE GENERALLY BETTER FOR OLDER PATIENTS THAN FOR YOUNGER ONES. THERE WAS NO REDUCTION IN COMPLAINTS OF CRIMINAL ACTIVITY FILED WITH POLICE IN THE PRECINCT SERVED BY THE ARTC PROGRAM (RELATIVE TO SURROUNDING PRECINCTS). STUDY FINDINGS SUGGEST THAT FUTURE DRUG TREATMENT PROGRAMS SHOULD DO THE FOLLOWING: (1) USE AGGRESSIVE OUTREACH TECHNIQUES, INCLUDING EPIDEMIOLOGICAL METHODS, TO REACH YOUNGER ADDICTS; (2) DEVELOP SOUND ADMINISTRATION AND MAKE A COMMITMENT TO A LONG TERM EFFORT; AND (3) SCREEN PATIENTS CAREFULLY AND PROVIDE AN INTEGRATED, BROADENED RANGE OF SERVICES COMBINING MAINTENANCE AND DRUG-FREE APPROACHES. SUPPORTING DATA AND A LIST OF REFERENCES ARE INCLUDED. (AUTHOR ABSTRACT MODIFIED--LKM)