Although it is one of the most widely researched personality correlates of psychological reactions, the relationship between negative affectivity (NA) and physiological arousal has received little attention. This study examined the associations between NA and physiological outcomes of heart rate, skin temperature, and muscle tension. The authors hypothesized that when individuals are in a stressful situation, persons high in NA experience more heightened physiological arousal than those low in NA. After personality and demographic data were collected, 230 individuals participated in a stressful intervention. Individuals high in NA experienced a significantly greater rate of increase in electromyogram during the stress intervention and a lesser rate of decrease in electromyogram after the stressful event than those low in NA. In regard to skin temperature, those high in NA did not recover from the stress intervention as well as those low in NA. Negative affectivity was not related to heart rate.