There is considerable evidence linking increased rates of crime in nonincarcerated substance-abusing populations to increased use of both heroin and cocaine, including crack. The relative contributions of the use of these and other illicit substances to the self-reported criminal activity prior to incarceration have received little research attention. The need for such investigations is important in view of the increased availability of cheaper, more potent forms of heroin and cocaine. Self-report information was examined from a structured interview on the drug use, employment status, drug distribution income, and criminal behavior of 188 primarily African-American drug-abusing offenders in the 6 months prior to the commission of the offense for which they were incarcerated. Predictor variables were drug use patterns, income, gender, age, and age at first crime. The results showed that, prior to incarceration, the use of opioids was significantly related to a greater frequency of criminal activity. Drug distribution offenses, particularly dealing, by both men and women constituted the predominate criminal activity. A higher proportion of men than women were involved in violent crime, and a small percentage of subjects were responsible for a disproportionate share of violent offenses. The most violent male offenders were significantly younger at commission of first crime and were engaged in a greater variety of offenses in the period preceding their instant offense. Male gender was significantly associated with the commission of a greater variety of crime. Both younger age and male gender were associated with the commission of more severe criminal activity. Fewer months worked and greater income from drug distribution were both significantly related to a greater frequency of total crime committed. Those individuals for whom this source of income was especially profitable were more likely to have engaged in violent criminal activity. It is important to monitor not only drug use but also legitimate employment and provide job-seeking skills and training in the rehabilitation and social reintegration of substance-abusing offenders. 5 tables, 1 note, 53 references