OBJECTIVES: Stressor appraisals are a transaction between the environment and the individual, such that individuals may appraise a situation as stressful when the problem is greater than the resources available to address it. Stressors appraised as threatening to the way one feels about themselves, their plans for the future, or their own physical health and safety are known to increase negative affect. Appraisal theory frames our predictions regarding the importance of daily contexts and aging processes to understand how stressor appraisals and feelings of aging may be associated with daily affective ratings. We investigated the potential interaction of daily stressors appraisals and daily subjective age on daily negative affect. METHODS: 101 younger adults (aged 18-36, M = 19.4, SD = 2.05) and 73 older adults (aged 60-90, M = 65.2, SD = 4.66) participated in an online 8-day daily diary study. RESULTS: Our results indicated a significant 2-way interaction between daily stressor appraisals and daily subjective age on daily negative affect, such that on days when participants reported low stress appraisals and younger subjective ages, participants also reported lower negative affect. DISCUSSION: The dynamic nature of stressor appraisals, in light of daily aging experiences and daily affective ratings, suggests potential benefits and boundaries associated with subjective aging experiences.