Sixty‐four undergraduate males received either very postive or very negative personal evaluations from an attitudinally similar or dissimilar stranger, and were then given an opportunity to aggress against this person by means of electric shock. Half were exposed to these stimuli under comfortably cool environmental conditions, while half were so treated under uncomfortably hot conditions. It was predicted that aggression toward the victim would increase as the degree of negative affect induced among subjects by the experimental conditions increased up to moderate levels, but that beyond this point, further increments in negative affect would actually tend to inhibit such behavior. A significant (p<.007) curvilinear relationship between negative affect and aggression supported these predictions, and suggested that such affect mediates the influence of high ambient temperatures on human aggressio