It has been evidenced that, with aging, older adults exhibit increased behavioral and physiological responses to stress. Older adults also often experience declines in executive functioning performance. The acute psychological stress induced through the Trier Social Stress Test (TSST) has been evidenced to negatively impact executive functioning in young adults. This relationship, however, has yet to be examined in older adults. In the current thesis, two experiments were conducted to investigate the effects of stress on executive functioning (Experiment 1), as well as age related differences in stress responsivity and in the effect of stress on executive functioning (Experiment 2). In Experiment 1, acute stress exhibited a negative effect on executive functioning. In Experiment 2, there were no age differences in stress responses, and a positive effect of acute stress on executive functioning in young adults only. The contradictory findings encourage further research on the effects of stress on executive functioning, and how they may differ between young and older adults.