Hypothalamic-pituitary-adrenal (HPA) axis function may change over the course of aging, and altered diurnal or stress-induced secretion of the hormone cortisol could predispose older adults to negative health outcomes. We propose that psychological resilience may interact with diurnal cortisol to affect health outcomes later in life. Emotion regulation and social support are two constructs that contribute to resilience and exhibit age-specific patterns in older adults. Determining how the use of resilience resources interacts with age-related diurnal cortisol will improve our understanding of the pathways between stress, resilience, and well-being. In this review, we assess published studies evaluating diurnal cortisol in older adults to better understand differences in their HPA axis functioning. Evidence thus far suggests that diurnal cortisol may increase with age, although cross-sectional studies limit the conclusions that can be drawn. We also review extant evidence connecting age-specific signatures of emotion regulation and social support with diurnal cortisol. Conclusions are used to propose a preliminary model demonstrating how resilience resources may modulate the effects of cortisol on health in aging.