Although thee is a widely held belief that drug users often commit crimes to obtain money for drugs, available data from studies on the subject are not conclusive. This study focused on the nonmedical use of psychoactive drugs and detailed information about the respondent's experience with drugs was obtained. In addition the men in the sample were asked if they had ever committed each of 10 illegal acts and, if so, the first and last year they did so. Findings showed that more than 90 percent of the men who reported an armed robbery had used illicit drugs, and 47 percent of them had used heroin at some point in their lives. In contrast, more than one-half of the men who did not report any of the seven criminal acts had not used an illicit drug, and only 2 percent of them had used heroin. Heroin users had reported 20 times more face-to-face thefts than nondrug users. When the respondents were classified according to the most serious crime reported, it was found that the men who committed the more serious crimes were more likely to report using each of the illicit drugs. It was concluded that involvement in criminal activities is strongly associated with use of illicit drugs, and that those who committed the more serious crimes were those who were most involved with drugs. Although use of illicit drugs did not seem to increase involvement in more serious crimes, those who reported both illicit drug use and serious criminal activity indicated that the criminal activity was carried out more often during the period of drug use than before or after that period. In delineating crime periods, more of the respondents who reported criminal activity used illicit drugs after the period in which they committed the various criminal acts than while they were doing so. Nine references and 11 tables are included.