Published in 1994, the fourth edition of the Diagnostic and Statistical Manual of Mental Disorders, known as DSM-IV, lists mental disorders and their symptoms. Psychiatrists and other health professionals use it as a guide in diagnosing and treating patients. In this article, the authors point out that, though most changes in the latest DSM were made to improve its usefulness, the changes were field-tested for reliability and validity but not for how useful they are to clinicians. Does it help a clinician, for example, if the manual lists six possible symptoms of a particular mental disorder, stating that any two will justify the diagnosis, whereas previous editions of DSM advised readers to base their diagnosis on five out of 15 symptoms? The authors note that DSM changes have some negative consequences: users must learn about them, for example, and they complicate the task of researchers who must compare data from studies that relied on different editions of the manual. The authors propose their own definition of "clinical utility," a term that has not been formally defined in the past. They recommend that future field trials assess how useful changes are to clinicians and suggest ways to make that assessment.