Physicians, including psychiatrists, give a lot of thought in their everyday work to answer the question of whether or not a particular patient has a disorder; they rarely give much thought to the broader issue of what constitutes a disorder. Remarkably, and consistent with the harmful dysfunction (HD) analysis, there is a broad consensus in both the general public and the medical and health professions as to what conditions are disorders--even though there is no consensus definition of disorder. The HD analysis is a substantial advance over previous attempts to define disorder in specifying the nature of what is not working in the individual (the dysfunction). The adoption of the HD analysis in DSM-V (Diagnostic and Statistical Manual of Mental Disorders, 5th ed.) would probably have little if any effect on the list of categories of mental disorders. Its main value would be in helping make revisions in the diagnostic criteria more valid as true indicators of disorder.