The severity of criminal behavior from the ages of 11 through 14 for three groups of urban males was studied. One group was made up of narcotic addicts. A second group consisted of never addicted men who had been associates of the addicts at the age of 11 (peer control group). The third group also had never been addicted but never associated with the addicts and was drawn from the community at large (community control group). Researchers began with the assertion that criminal activity in early adolescence is an indicator of future deviance. It was expected that the prevalence and severity of early criminal behavior would be highest for the most deviant group (the addicts) and lowest for the least deviant group (the community control group). This was supported by the study. In addition, it was found for the addicts that the younger the subject was when he first became addicted, the more serious the crimes in which he was likely to have been involved. Furthermore, regardless of the age at the onset of drug addiction, the addict group had the largest increase in the proportions of subjects involved in crime particularly at the more serious levels of crime. Data from this study may be useful in intervention programs which attempt to interrupt criminal behavior before it increases in severity. 4 tables, 3 figures