Chronically hostile persons may be at greater risk of cardiovascular illness, perhaps because of their more pronounced physiologic responses to interpersonal stressors. The present study of married couples examined the association between Cook and Medley Hostility (Ho) Scale scores and cardiovascular reactivity while couples were engaged in a discussion task with or without an incentive to exert control over their partner. Cynical hostility was associated with greater heart rate (HR) reactivity among husbands in both conditions and with greater systolic blood pressure (SBP) reactivity among husbands attempting to influence their wives. Further, husbands' cynical hostility was associated with greater SBP reactivity in their wives. Wives' cynical hostility was unrelated to their own or their husbands' reactivity. These results underscore the importance of social contexts in the association between hostility and psychophysiologic processes and suggest that the motive to exert social control may be important for hostile persons.