A number of constructive ideas are contained in this article. One such idea is that to use the term 'illness' for certain deviant behaviors may be to enlarge the category of 'illness' in a useful way, much as including the platypus within the category of Mammalia broadened that category, which then suggested other possibilities. The alternative is to view 'illness'—as applied to deviant behavior—as a misuse of the term for reasons of social control, which may then obscure investigations into the interrelationships between the bio-psycho-social systems.