Social anxiety disorder (SAD) is a pervasive problem associated with debilitating impairments in social settings. This research explored the affective and physiological reactions to social evaluation and examined the efficacy of an arousal reappraisal intervention in altering cardiovascular reactivity and affective responses. Across two studies, socially anxious participants exhibited a disjunction between subjective ratings and physiological responses. Whereas anxious individuals reported more anxiety and negative affect during a stressful public speaking task relative to nonanxious controls, no differences emerged in physiological reactivity as a function of anxiety. In the second experiment socially anxious and nonanxious participants instructed to reframe stress arousal as a positive coping tool exhibited reduced attentional bias and improvements in physiological functioning: decreased vasoconstriction and increased cardiac efficiency. This research suggests that outcomes in SAD may be improved by reappraising stress arousal.