**Title:** Hierarchy Stability Moderates the Effect of Status on Stress and Performance in Humans. **Authors:** Erik L. Knight, Pranjal H. Mehta **Abstract:** High social status reduces stress responses in numerous species, but this stress-buffering effect of status may dissipate or even reverse during times of hierarchical instability. In a novel experimental test of this hypothesis, 118 participants (57.3% female) were randomly assigned to a high or low status position in a stable or unstable hierarchy and were then exposed to a social-evaluative stressor (a mock job interview). High status in a stable hierarchy buffered stress responses and improved interview performance, but high status in an unstable hierarchy boosted stress responses and did not lead to better performance. This general pattern of effects was observed across endocrine (cortisol and testosterone), psychological (feeling in control), and behavioral (competence, dominance, and warmth) responses to the stressor. The joint influence of status and hierarchy stability on interview performance was explained by feelings of control and testosterone reactivity. Greater feelings of control predicted enhanced interview performance, whereas increased testosterone reactivity predicted worse performance. These results provide direct causal evidence that high status confers adaptive benefits for stress reduction and performance only when the social hierarchy is stable. When the hierarchy is unstable, high status actually exacerbates stress responses. **Significance Statement:** High-status leadership roles are theorized to reduce stress compared to subordinate roles, but higher rank is not always stress free. Here we demonstrate that high status inhibits stress responses and improves performance during a mock interview in a stable hierarchy, but high status boosts stress responses and carries no performance advantage in an unstable hierarchy. Feeling in control was an asset for interview performance, but increased testosterone reactivity was a liability. These findings have applications for improving outcomes in stressful evaluative settings, such as job interviews, and may hold translational implications for the influence of status on health. **Please see each sub-page wiki for file details.**