A university-affiliated psychiatric inpatient unit in a private general hospital is an organization which serves many purposes. However, the primary purpose is quite evident: to provide various psychiatric therapies to patients with diverse psychopathologies. This becomes extremely complicated if the unit attempts an eclectic approach. Thus, the unit must consider: (1) psychopathological frameworks such as genetic, sociocultural, psychoanalytic, behavioral, and biochemical etiologies; (2) therapeutic interventions such as individual, group, and family therapy; insight-oriented, supportive, and behavioral psychotherapy; milieu therapy; and psychopharmacological treatment; (3) the various philosophies, attitudes, and skills of the multidisciplinary team of psychiatrists, psychologists, nurses, aides, social workers, activities therapists, expressive therapists, and administrative support personnel. General systems theory and general living systems models may further the conceptualization and understanding of the inpatient unit. This, in turn, may improve patient treatment. For the inpatient psychiatric unit, we describe the 19 critical subsystems of general living systems theory, with special emphasis on the decider subsystem.