During the study's main collection period, 1980-82, staff collected data on 201 heroin abusers (75 percent male, 55 percent black, and 44 percent Hispanic). Vignettes and statistical data describe the criminal activities, drug-use patterns, and differing lifestyles of heroin abusers. Study results show that heroin abusers commonly use other drugs; that daily heroin users are more criminally active than other heroin users; and that persons tend to sell the drugs they use most frequently, using the proceeds to support their drug habit. The study provides quantitative information on drug abusers' crime rates, the criminal income gained from these activities, and abusers' yearly income and cash expenditures. A review of economic consequences addresses the specifics of who gains and who loses from heroin abuser criminality. It contends that while the heroin abusers receive poor pay for their crimes, their crimes and productivity in the underground economy benefit more persons than suffer losses. The study also examines heroin abusers who commit robbery, showing that robberies are only a small part of their criminality. Study data also reveal that most serious criminals are avoiding treatment for their drug abuse and also appear reasonably successful in avoiding serious criminal charges. The authors propose that heroin abusers are both victims and victimizers -- for all their entrepreneurial skills they are merely the exploited day laborers in the retail drug business. Policy implications of the research are discussed. A detailed explanation of the study's methodology and data validity concerns is provided as is tabular study data. Over 200 references and an index are included.