The provision of explicit and specific diagnostic criteria in the Diagnostic and Statistical Manual of Mental Disorders (DSM; American Psychiatric Association, 1980, 1987) was instrumental in the production of a substantial amount of informative research. The major emphasis in the preparation of the DSM-IV has been to maximize the impact of this accumulating research on the revision and to document the rationale and empirical support for any changes that are made. In this article we discuss the empirical basis for the DSM-IV. The historical context provided by the previous editions is briefly presented and followed by a description of the process by which the DSM-IV is being constructed. The input of empirical data through literature reviews, data reanalyses, and field trials is described, and an illustration with the antisocial personality disorder diagnosis is given.