The physiologic and behavioral responses of man in a social setting were studied. Groups of individuals were brought together and asked to perform a meaningful task which created a situation of stress. The interrelationships of the individuals were controlled as to group cohesiveness and relative abilities. Changes in plasma free fatty acid levels were used as an index of physiologic response, and the degree to which the individual conformed to the group was used as an index of behavior. It was observed that the physiologic response was most marked when the individual was the most able in a tightly-knit group or the least able in a discordant group. Conforming behavior during the latter phases of the study appeared to reduce the degree of physiologic responsiveness. It was concluded that the characteristics of the social relationships of individuals are important variables in determining the physiologic response to stress, and that conforming behavior may modify these responses.