Previous studies have found that an individual's perception of control in a situation (Locus of Control; LOC) can serve as a protective factor that has physiological and psychological benefits. The present study examines LOC in an acute stress paradigm to examine the relationship between LOC and hypothalamic-pituitary-adrenal axis functioning as well as between LOC and performance. One hundred and thirteen participants at a metropolitan university were randomly assigned to either a stress or control condition. The stress condition consisted of the Trier Social Stress Test (TSST) while the control condition consisted of viewing a neutral travel video. Salivary cortisol was measured at four time points before and after exposure to the assigned condition. A mock job interview speech in the TSST was recorded and evaluated for performance on eight dimensions. LOC significantly predicted cortisol reactivity to the stressor in a multiple linear regression model. In addition, LOC was a significant predictor of speech performance in a simple regression model. Cortisol was not related to speech performance, and LOC did not moderate this relationship, although LOC uniquely predicted speech performance. This research adds to a growing body of literature demonstrating physiological and functional influences of LOC orientation.