The article seeks to sum up all that has been said on the subject of professional criminality in the past half-century. It was never any part of the author's aim to offer an analysis of contemporary professional crime. He viewed his task in much more modest terms. First of all he presents the origins of professional crime in a historical perspective and adduces the traditional definitions of the phenomenon dating to the first decade of the 20th century. Next he addresses the issue of empirical determination of the scale of professional crime and presents more recent approaches to description of this kind of criminality and attempts to define the concept of professional criminal. In an account with a primarily sociological focus the emphasis is on the origins of professional criminality seen as one of many mechanisms regulating the behavior of individuals. The so-called traditional method of defining professional crime, given currency by European legal theorists and American sociologists in the first half of the 19th century, has come under criticism in recent decades. Researcher representing various theoretical schools have gathered empirical evidence that calls in question the existence of a category of professional criminals who make their living solely from crime, specialize in one kind of crime and are closely connected with the criminal world, the latter being their point of reference and source of norms and rules of conduct. The reality seems to be more complicated. Among criminals there are some who are beyond question professionals and specialists in some area of activity but have never belonged to any sort of criminal community.