THE HEROIN USER PROPERTY CRIME ESTIMATE IN THIS STUDY IS DEVELOPED AND DISCUSSED FOR 1974, THE BASE YEAR OF THIS REPORT. PRIMARY PURPOSES OF THIS PAPER ARE TO ESTIMATE THE NUMBER AND COSTS OF CRIMES COMMITTED BY HEROIN USERS, TO PROVIDE AN OVERALL ESTIMATE OF U.S. PROPERTY CRIMES, TO DISCUSS CRIMINAL ACTIVITY OF HEROIN USERS IN RELATION TO OTHER INCOME PRODUCING BEHAVIOR, AND TO EXAMINE ISSUES IN HEROIN RELATED CRIME. THE PAPER FIRST PRESENTS BACKGROUND MATERIAL ON THE SUBJECT OF HEROIN RELATED CRIME THROUGH AN EXAMINATION OF THE MOST COMMON APPROACHES TAKEN TO ESTIMATE OR EXAMINE THE PROBLEM. AN IN-DEPTH ESTIMATE OF HEROIN RELATED CRIME IN THE U.S.A. IS THEN DEVELOPED. IT IS ESTIMATED THAT HEROIN USERS COMMITTED $3.9 BILLION WORTH OF PROPERTY CRIME IN 1974. THIS REPRESENTS ABOUT 19 PERCENT OF ALL PROPERTY CRIMES IN THE UNITED STATES. THE SIZE OF THE HEROIN USERS' HABIT WAS DIRECTLY PROPORTIONAL TO THE EXTENT OF HIS CRIMINAL BEHAVIOR, WITH SERIOUS USERS COMMITTING MOST PROPERTY CRIMES. IN CONCLUDING, THE AUTHORS CAUTION THAT IT CANNOT BE ASSUMED THAT THE ELIMINATION OF ALL HEROIN IN THE U.S. WOULD ELIMINATE ALL CRIMES COMMITTED BY HEROIN USERS, SINCE THIS WOULD ASSUME THAT THE USERS' LIVES WOULD HAVE BEEN FREE OF CRIME, BUT FOR THE USE OF HEROIN. (AUTHOR ABSTRACT MODIFIED)...DMC