There has recently arisen among certain psychiatrists a tendency to stress unduly the role of the hypothalamus as a dynamic "source" of emotion and even of "drive" or instinct. A critical evaluation of the evidence, however, reveals the following:1. Animal experimental work on the hypothalamus has indicated that this structure integrates and may possibly reinforce the effector neural impulses controlling some of the sympathetic and motor manifestations of emotion; however, there is little or no basis for the belief that the hypothalamus governs or even mediates the affective experiences themselves.2. On the other hand, work in this laboratory has furnished evidence that such a direct psycho-somatic localization probably does not exist, inasmuch as (a) the reactions induced by stimulation of the hypothalamus do not significantly modify spontaneous behavior, (b) animals with extensive hypothalamic lesions can apparently react in an integrated affective manner, (c) animals subjected to prolonged conditioning procedures or to the induction of an experimental neurosis do not learn to respond to hypothalamic stimulation in ways analogous to their spontaneous or experimental adaptations to emotionally significant situations.3. The clinical and pathological evidence as to the role of the human hypothalamus in emotional experience is not conclusive.4. It would, therefore, seem safest in the present state of our knowledge to assign to the hypothalamus its experimentally demonstrable role in reinforcing and coordinating the neural and hormonal mechanisms of emotional expression, and reserve for adequate proof the hypothesis that it is either the dynamic source or the seat of experience of affective states. On the other hand, much experimental, psychological and clinical evidence clearly indicates that an emotion is a highly complex psychobiological phenomenon in which not only the central nervous system, but the entire body functions as a whole in its multiple adjustments to its milieu.Abstract Teaser