tAdolescents change how they cope with stress across different situations, but also differ from one anotherin their general capacity to cope. The current study examined whether cortisol reactivity to perceiveddaily stress varies with both situational (within-person) and individual (between-person) differences incoping. First-year college students (N = 63; Mage= 18.85) provided 15 stress-coping diaries and 15 cor-responding saliva samples across 3 weekdays. Results from hierarchical linear growth models revealedthat perceiving greater stress than usual in the last hour was significantly associated with elevations incortisol (relative to diurnal patterning) only during situations characterized by greater than usual diary-reported engagement coping. Regarding individual differences, perceiving greater stress than usual wassignificantly associated with elevations in cortisol only for adolescents below average on trait measuresof engagement coping or belief in their ability to handle stress. Findings indicate that cortisol reactivityto daily stress varies with both situational variation and individual differences in coping.