A theory of the response to chronic intermittent stress, intergating many diverse studies, is presented. Chronic intermittent stress is presumed to be the type of stress most frequently encountered and most likely to cause physiological changes which predispose an organism to tissue damage. The theory states that all organisms are genetically predisposed to adapt to stress and that the physiological pattern of adaptation is similar across species. This pattern consists of a conditioned endocrine response before the stressor is presented accompanied by a decrease in arousal during the stress. These changes occur because the organism is predisposed to learn cues predictive of stress and to assess the threat potential of the stressor. This pattern is adaptive because it conserves resources and promotes homeostasis. Maladaptation is discussed in terms of failure to learn situational expectancies and appropriate responses. Implications of this theoretical perspective are examined.