THE SUBJECTS OF THE STUDY WERE 80 MISUSERS OF HEROIN WHO LIVED IN NEW TOWN OF CRAWLEY, WEST SUSSEX, GREAT BRITAIN. THE RELATIONSHIP BETWEEN THEIR CRIMINAL HISTORIES AND THEIR HISTORIES OF DRUG ABUSE WERE EXAMINED. IT WAS FOUND THAT MORE OF THE HEROIN USERS THAN WOULD BE EXPECTED HAD BEEN CONVICTED OF CRIMINAL OFFENSES BEFORE THEY BEGAN TO ABUSE DRUGS, WHILE THE REDUCTION OR CESSATION OF HEROIN USE DURING THE 4-YEAR FOLLOWUP PERIOD WAS ACCOMPANIED BY A REDUCTION IN CONVICTIONS. SOME SOCIAL CHARACTERISTICS OF THE MALE HEROIN USERS WERE COMPARED WITH THOSE OF THE TWO OTHER CRAWLEY GROUPS -A GROUP OF JUVENILE OFFENDERS WHO DID NOT USE HEROIN AND THE CONTROL GROUP OF NONDELINQUENTS. CHARACTERISTICS COMMONLY ASSOCIATED WITH MALADJUSTMENTS DID NOT DISTINGUISH THE HEROIN USERS FROM THE JUVENILE OFFENDERS, NOR WERE THEY FOUND TO BE ASSOCIATED WITH THE CONTINUED USE OF HEROIN. ANALYSIS OF THE DATA IN EPIDEMIOLOGICAL TERMS SUGGESTED THAT AMONG THE NECESSARY CONDITIONS FOR AN OUTBREAK OF DRUG MISUSE IN A PARTICULAR COMMUNITY, THE AVAILABILITY OF DRUGS TOGETHER WITH SOCIALIZING DRUG USERS WERE MORE IMPORTANT THAN THE PRESENCE OF PREDISPOSED INDIVIDUALS. REFERENCES AND SUPPORTING DATA ARE INCLUDED. (AUTHOR ABSTRACT MODIFIED--TAO)