RAPID growth in the number of early discharges from mental hospitals made possible by the use of psychopharmacologic agents has led to an increasing interest in the effectiveness of community-based nursing care in the rehabilitation of the mentally ill. Recent studies of programs in Ohio and Georgia have been described,1'2 and an ambitious demonstration is now being launched in Montgomery County, Md., which will include an extension of nursing services rendered to mentally ill patients and their families. A research grant from the National Institute of Mental Health made it possible to undertake an evaluation of the effectiveness of the services rendered by the Instructive Visiting Nurse Association of Baltimore City (IVNA) to patients admitted to a state mental hospital and to their families. This paper is concerned with the purpose, study design, and the main results of the completed evaluation. Following an extensive review of its program, IVNA decided in 1957 to initiate a new mental hygiene nursing service based primarily on home visits and the counseling of members of families in which an adult had recendy been hospitalized in a state institution. The hypothesis entertained was that such visits and counseling would (1) reduce the total length of hospitalization required by the patient, (2) improve the capabilities of the family to interact with the patient so that he would attain a socially useful status, and (3) accelerate the patients return to his optimal prehospital status. Although the hypothesis was reasonable, a critical attitude seemed the order of the day in view of the pattern of enthusiasm, doubt, and disappointment which had accompanied many prior innovations in mental hygiene programs. The validity of the hypothesis would rest upon a demonstration that the nursing service significantly reduced the need for hospitalization during a specified study period (18 months), or improved the patient's capability to interact with members of the immediate family, or increased his capability to participate in the social and economic life of the community.