THE STUDY GROUP WAS COMPOSED OF 200 GENERAL ARRESTEE POPULATION SUBJECTS WHO WERE IDENTIFIED AS REGULAR OPIATE USERS IN INTERVIEWS BY TASC ('TREATMENT ALTERNATIVES TO STREET CRIME') PROJECT PERSONNEL IN DENVER CITY JAIL DURING LATE 1973 AND EARLY 1974. THE SUBJECTS WERE INTERVIEWED TO DETERMINE DEMOGRAPHIC, DRUG USE, AND SELF-REPORT CRIMINAL HISTORY DATA; ARREST DATA WAS COLLECTED FROM OFFICIAL RECORDS. STUDY RESULTS SHOWED SIGNIFICANT INCREASES IN CRIMINAL ACTIVITY ASSOCIATED WITH THE ONSET OF ADDICTION, AS EVIDENCED BY A 200 PER CENT INCREASE IN IMPACT CRIME ARRESTS AND A 250 PERCENT INCREASE IN ALL NON-DRUG ARRESTS FOR THE ENTIRE STUDY GROUP. THE CRIMINAL ACTIVITY INCREASE WAS DISPLAYED IN VIOLENT CRIME CATEGORIES AS WELL AS PROPERTY ACQUISITIVE AND DRUG OFFENSE CATEGORIES. SOME DIFFERENCES WERE APPARENT ACCORDING TO AGE OF ONSET OF ADDICTION, RACE, AND GENDER, BUT THE STUDY DESIGN DID NOT WARRANT THE DRAWING OF DEFINITE CONCLUSIONS REGARDING THE DIFFERENCES. REFERENCES ARE INCLUDED. (AUTHOR ABSTRACT MODIFIED)