Classification and psychopathology research.

The classification of psychopathology appears to be at a crossroads, with a new version of the Diagnostic and Statistical Manual of Mental Disorders impending and one of the current aspirations of the National Institute of Mental Health being the development of new ways of classifying mental disorders. This article discusses what we currently know about psychopathology and the role that classification has played in psychopathology research. It is pointed out that a wide variety of etiological factors, both within and outside the individual, have been implicated in the etiology of psychopathology, and that there is no empirical or conceptual reason to privilege any particular level of explanation. The ways in which signs/symptoms and disorders may be related are discussed, including their implications for classification. The value of theory development and theory-driven research is emphasized, along with the potential perils of generating an ossified classification scheme that must be adhered to.