Arguing that Gottfredson and Hirschi have misrepresented the aforementioned concepts and the authors' research on these topics, the article reviews the author's definitions of these concepts as used in their research. The article explains that the concept of a criminal career, the distinction between participation and frequency, and the longitudinal research method have considerable value for criminological theory and policy. Specifically, the article reasons that the individual frequency of offending stays constant with age while participation in offending varies with age. Although the authors are not enthusiastic supporters of the concepts of career criminals and selective incapacitation, they do believe these concepts can stimulate important research, although the outcome of debate over these policies has little relevance for the value of research on criminal careers, the participation/frequency distinction, and the longitudinal method. 26 footnotes, 6 figures, and 47 references.