Participants came from 54 drug treatment programs. The majority were opiate-dependent polydrug users. Drug treatment staff gathered information by means of individual structured interviews. The participants reported committing more than 27,000 acquisitive criminal offenses in the 3 months prior to starting treatment. Shoplifting was the most common offense. Ten percent of the participants were responsible for three-fourths of the crimes. Two other groups of participants were the low-rate offenders and the individuals who did not commit an acquisitive crime. Multivariate analyses revealed that the frequency of illicit drug use was associated with increased levels of criminal behavior. The high-rate offenders were 11 times more likely than the no-crime group to be regular users of heroin and were 3 times more likely to have used cocaine regularly. Findings suggested that the most dependent an problematic drug abusers present treatment services with the greatest challenge in terms of reducing levels of criminality. Tables and 35 references