Many past studies of data on deinstitutionalization have used an overly simplistic and often misleading approach, which has led to a number of "myths" of deinstitutionalization. The authors present data on the changing mental health service system collected by the Division of Biometry and Epidemiology of the National Institute of Mental Health, and they analyze the data to reveal trends that disprove a number of the commonly accepted myths. Through their analysis they show that outpatient care has not replaced inpatient care, that public institutions, particularly state mental hospitals, have not been replaced by community-based facilities, and that private resources have not replaced public ones as the bearer of the cost of caring for the mentally ill. They conclude that the availability and quality of mental health services and the effect of these services on patients and their communities are difficult issues for future research.