The "professional thief" is a highly specialized predatory offender with a history that dates back to Elizabethan England. Although this type of criminal is generally associated with narcotic addiction, his drug-taking typically involved the use of heroin, morphine, and cocaine on an intermittent basis. However, trafficking in drugs was common to the "professional" underworld, and as a result this deviant fraternity had a notable impact on the impressment of a criminal model of drug use on twentieth century conceptions of the addict. The concept of "professional" theft is reviewed, the use of drugs by professional thieves is discussed, and the interaction between this underworld group and the early Federal Bureau of Narcotics is examined.