Some studies show that enhanced control increases cardiovascular reactivity; other studies show decreases. This disparity may be due to a confound: enhanced control may reduce reactivity, but effort accompanying active coping may increase it. The present study was designed to vary level of control and availability of active coping responses, while maintaining effort constant. Sixty female undergraduates performed word-search puzzles while blood pressure and heart rate were monitored. They were divided into three groups: In condition 1, reinforcement was contingent on the subjects' performance only; in conditions 2 and 3, reinforcement was contingent on the joint performance of the subject and a poorly performing confederate. In condition 2, subjects could help their partners (active coping); in condition 3, they could not (passive coping). Effort was constant across groups. Cardiovascular responses were significantly greater in the passive coping condition than in the other two, indicating that with effort held constant, enhanced control diminishes reactivity.