Building on prominent theories of emotional aging (Carstensen, 2006; Charles & Luong, 2013), this study investigated age differences in the variability and situational sensitivity of emotion regulation strategies. We hypothesized that, older, as compared to younger, adults would demonstrate greater temporal variability in their use of emotion regulation strategies and adapt them more flexibly to the perceived controllability of daily stressors. Over 28 days, younger adults (n = 133, Mage = 24.95 years, SD = 2.79, 49% female) and older adults (n = 119, Mage = 69.50 years, SD = 3.50, 61% female) reported their use of cognitive reappraisal and situation modification strategies in relation to their most stressful situation each day. They also rated the perceived controllability of these situations. Analyses revealed multidirectional age differences in the variability of strategy use: Older adults showed greater temporal variability in situation modification but less variability in cognitive reappraisal, compared to younger adults. Additionally, there were significant age differences in how situation modification strategies were adapted to the perceived controllability of stressors. The within-person correlation between stressor controllability and situation modification use was stronger in older adults than in younger adults. In contrast, no such age differences were found for cognitive reappraisal strategies. These effects remained robust even after controlling for various person- and stressor-related characteristics. Overall, our results suggest that age differences in the ability to flexibly adjust emotion regulation strategies to specific situations might depend on the strategy used. Further research should examine additional situational characteristics and emotion regulation strategies. (PsycInfo Database Record (c) 2025 APA, all rights reserved).