We predicted that adopting a performance-approach vs. performance-avoidance goal would lead to physiological responses characteristic of psychological states of challenge vs. threat appraisals, respectively. Furthermore, we predicted that these states would mediate the effects of goals on performance. Twenty-seven undergraduate females performed a task described as identifying either exceptionally strong performers (performance-approach goal) or exceptionally weak performers (performance-avoidance goal). Participants' cardiovascular reactivity (CVR) was recorded while they performed the task. As predicted, participants in the performance-approach goal condition performed better on the task than did those in the performance-avoidance goal condition. Also as predicted, those in the former condition exhibited a challenge pattern of CVR whereas those in the latter condition exhibited a threat pattern of CVR. Furthermore, physiological responses mediated the effects of performance-based goals on performance.