Self-compassion has been identified as a psychological resource for ageing well. To date, self-compassion among older adults has typically been conceptualised as a trait variable. This study examined whether day-to-day (state) variability in sef-compassion was associated with negative affective reactivity to daily stressors. Daily diary assessment methods were used to examine the potential moderating role of between- and within-person self-compassion on the relationship between daily stressors and negative affect. A community-based sample of 107 older adults aged 65+ completed questionnaires once daily over 14 days. Multilevel modelling revealed that 37% of the variance in self-compassion occurred within-persons. Daily self-compassion moderated the relationship between daily stressor exposure and daily negative affect. On days with greater stressor exposure than usual, older adults showed less negative affective reactivity on days when self-compassion was higher, compared with days when self-compassion was lower. No modertaing effects were observed for between-person (trait) self-compassion. These findings suggest that self-compassion in older adults should be conceptualised as both a state and trait variable and that state self-compassion may be protective in the stress-reactivity pathway. Future research should investigate whether brief self-compassion interventions might help older adults to avoid or down-regulate negative emotions in response to stressors.