Prior research suggests variability of positive affect (PA), or the degree to which an individual's experience of PA is variable rather than stable, is associated with worse psychological health. However, it is unclear whether different aspects of PA variability serve different psychological functions. One possibility is that changes in PA in response to rewarding contexts, or PA reactivity, serve a healthy function, while general instability of PA from one moment to the next serves an unhealthy function. The current investigation separated out PA reactivity to pleasant activities from general PA instability. We tested associations in three experience-sampling studies collected between 2012 and 2020 (N = 323). An internal meta-analysis revealed a significant association between PA reactivity to pleasant activities and less well-being. Moderation by average levels of PA was present but inconsistent across studies. We discuss how PA reactions to rewarding contexts may not necessarily reflect healthy emotion regulation and consider that "mood brightening" effects in daily life may indicate ill-being rather than well-being. Caution is warranted when interpreting the primary findings, as the indirect effect of PA reactivity was significant in only one of the three individual studies, and the effect was only found for the outcome of well-being and not distress. Results can be most confidently generalized to White adults living in the Midwest region of the United States. Future research should test not only the intensity of PA reactivity to rewarding contexts but also how long a person can sustain elevated PA-in relation to psychological health. (PsycInfo Database Record (c) 2024 APA, all rights reserved).