Discusses the changes in the delivery of mental health services from ancient Egypt and Greece to the present, emphasizing developments of the 20th century: the establishment of psychopathic hospitals, the increase in psychiatric units in general hospitals following World War II, and the use of ECS, lobotomies, and somatic therapies. The revolutionary era of the past 25 yrs is discussed, especially 2 developments: (a) the introduction of rauwolfia and the phenothiazines; and (b) psychosocial methods of treatment, including milieu therapy. The changing mental health system includes (a) the inmate decrease in public mental hospitals, (b) the rapid expansion of outpatient and ambulatory systems, (c) the shift from public to private hospitals, (d) the increase in public acceptance of mental health, and (e) the payment for mental health services by insurance companies. These trends are summarized as a shift from institutional to community settings and from the public to the private sector. Problems of deinstitutionalization are examined.