Since the close of World War II it has been increasingly clear that experts in the management of functional mental illness are being drawn from three professions—medicine, psychology, and social work. The basic structure of undergraduate medical training is essentially standard in a majority of American medical schools; most commonly there are two years of basic science instruction followed by two years of training and supervised apprenticelike experience in the clinical fields. The clinical psychologist holds the Ph.D. degree in psychology. This means that he has completed a minimum of three years of graduate instruction in psychology from a major university. Before admission to such graduate study, he has completed a four-year college degree in a liberal arts program with emphasis upon the humanities and the social sciences. The social worker has a knowledge of the network of city, county, and state welfare agencies, their personnel, equipment, and services and their administrative patterns and relationships.