The histories of 40 patients with functional psychosis who were undergoing chronic hospitalization were investigated with a case-study method based on a psychoanalytic reformulation of psychosis in terms of "developmental lines." Distinctions are drawn between psychic structure and "support," as maintainers of developmental progress, and between regression and developmental arrest. Two types of loss of support leading to psychotic regression were found—active, as a consequence of developmental ambition, and passive, by disappearance of a source of support. Progressive developmental arrest was found in only 17 patients at first admission. Errors precluded successful treatment in 39 cases: in 17 the patient's need for support was completely avoided; in another 17 dominant errors were made in identifying the need for support or in providing sufficient support; and in 5 treatment facilities were inadequate. One instance of relatively successful treatment was found.