Robert Michels, MD1; Allen Frances, MD2'Walsh McDermott University Professor of Medicine and Psychiatry, Cornell University, New York, New York.Correspondence: 418 East 71 Street, Suite 41, New York, NY 10021; rmichels@med.cornell.edu.'Professor Emeritus and former Chair, Department of Psychiatry, Duke University, Durham, North Carolina; Chair, DSM-IV Task Force.Correspondence: 1820 Avenida Del Mundo, Coronado, CA 92118; allenfrances@vzw.blackberry.net.Progress Is Preferable to StagnationPsychiatry is the branch of medicine that deals with people who are vulnerable to or troubled by mental, emotional, or psychological pain, distress, or disability, and for whom the profession may provide prevention, relief, support, care, treatment, cure, or rehabilitation. That is a broad definition; it could encompass most of the universe. However, at any given time, the scope of psychiatry, including the range of people who should be considered potential patients, is limited by the limits of psychiatric knowledge and capacity-for whom will psychiatric intervention make a difference? As that knowledge and capacity expand, so will the boundaries of psychiatry.Note that these boundaries are not limited by decisions of the profession, by its desire for influence or power, or by the deliberations of a committee writing a diagnostic manual. If the latter does its job well, it does not decide what the boundaries should become, it describes the boundaries that exist at that time. It also recognizes that they will change over time as new knowledge leads to the development of new interventions that make a difference where previously there were none-for example, dietary interventions that prevent the development of mental disability in infants vulnerable to phenylketonuria, psychosocial interventions that diminish the risk of posttraumatic stress disorder in trauma victims, or psychopharmacologic interventions for patients with mild chronic mood disorders. In each of these situations, people who were not previously viewed as psychiatric patients achieved that status because the psychiatric profession developed the ability to help them. Psychiatry is a relatively young profession, perhaps 250 years old. Over those years, psychiatry has grown immensely in its knowledge and its capacity to help people, and, as a result, its boundaries have expanded. It began with the care of patients with serious disability and psychosis, but new knowledge and new treatments have expanded its domain to encompass patients with less disability who could live in the community but not thrive, patients with mood or anxiety disorders who were not psychotic and did not require institutionalization, people with serious personality disorders, people with addictions, and others. None of these expansions resulted from a decision about diagnostic nosology or nomenclature. Each resulted from the recognition of a social need, dissatisfaction with the profession's capacity to respond, the search for new knowledge, the trial of new interventions, and the profession's and the public's recognition of the social value of defining new populations as psychiatric patients.It would be tragic if this process were to come to a halt-our capacity is too limited and people who need more than we can now offer are too numerous. We look forward to finer distinctions among people who suffer and greater precision in our capacity for differential therapeutics, a concept that 1 believe Dr Frances and his colleagues developed.1 Interventions that operate at the genetic or epigenetic level, developmental interventions that are targeted at patterns of mental functioning, and strategies for counselling parents raising vulnerable children, all have promise.Certainly we do not want a committee that sits around and, without reference to what is happening in the outside world, decides whom should be included in the current edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM). …