In an effort to provide timely information concerning the criminal activities of narcotic addicts in three different metropolitan areas, male narcotic addicts attending methadone maintenance/detoxification centers in Baltimore, Philadelphia, and New York City participated in extensive, confidential interviews conducted between May 1983 and April 1984. The information obtained focused on the amounts and types of crimes committed during the addict's longest period of active addiction to opiates, their derivatives and synthetics, as well as his first period of nonaddiction. Crimes committed were placed in one of five categories as follows: Theft, Violence, Drug Sales, Deception/Forgery, and Other. Several different measures of criminal activity were utilized, all embodying the concept of crime-days per year at risk. Such crime-days measures involve annualizing, i.e., the number of crime-days accumulated by each subject in each category during a specified time at large in the community is expressed as crime-days per year at risk by taking the ratio of crime-days to total days at large and multiplying by 365. Addicts were compared by race/ethnicity (Black, White, and Hispanic) within cities as well as by race/ethnicity across cities using one-way analysis of variance procedures. Addict crime rates were also compared for the period of active addiction and nonaddiction. Several mean differences by race/ethnicity within city, as well as by race across cities, were noted. Moreover, crime rates tended to be higher during the period of active addiction. In this sense, then, drugs may be said to“drive”crime.