Coping responses to stress can be divided into three broad categories. The first coping category involves voluntarily mobilizing social supports. The second category involves voluntary coping strategies like rehearsing responses to danger. The third coping category, like fever and leukocytosis, is involuntary. It entails deploying unconscious homeostatic mechanisms that reduce the disorganizing effects of sudden stress, DSM-5 offers a tentative hierarchy of defenses, from psychotic to immature to mature. The 70-year prospective Study of Development at Harvard provides a clinical validation of this hierarchy Maturity of coping predicted psychosocial adjustment to aging 25 years later, and was associated with not developing symptoms of post-traumatic stress disorder after very severe WWII combat.