The question is raised for further discussion: 'Is there any pragmatic virtue, from the standpoint of psychoanalytic psychology, in postulating a homeostatic instinct?' Various possibilities are explored. The conclusion is reached that many known physiological and psychological phenomena may indeed be correlated by regarding homeostasis as instinctually rooted. Thus regarded, homeostasis arises from an instinct whose aims include a stable but dynamic adjustment of the organism and, psychologically speaking, a maximum of security in a complex environment. The derivative tendencies of this instinct (both physiological and psychological) make for conservatism, order, repetition of the familiar, and, in times of crisis or threat, regression to what has proved successful in the past.