Multiple studies have confirmed a seemingly paradoxical finding that family caregivers have lower mortality rates than comparable samples of noncaregivers. Caregivers are often also found to report more symptoms of depression and higher stress levels, but psychological distress and mortality are rarely examined in the same study. This study tests a possible mechanism for the mortality effect by applying a theoretical model that posits psychological and physiological stress-buffering benefits from prosocial helping behaviors. Participants in the population-based REasons for Geographic and Racial Differences in Stroke (REGARDS) study included 3,580 family caregivers who were individually matched to 3,580 noncaregivers on 15 demographic, health history, and health behavior variables using a propensity score matching algorithm. Baseline measures of depressive symptoms and perceived stress levels were also collected. The results indicated that caregivers reported significantly more depressive symptoms and higher perceived stress levels than propensity-matched noncaregivers (ps < .0001). However, consistent with our previous analysis (Roth et al., 2013), an analysis of 7-year survival rates showed that caregivers had a 16.5% lower mortality rate than noncaregivers (hazard ratio = 0.835, 95% CI = 0.719, 0.970). Significant caregiving*psychological distress interaction effects supported the stress-buffering hypothesis. Both depressive symptoms and perceived stress scores were significant predictors of mortality for the matched noncaregivers (ps < .0001), but not for the caregivers (ps > .49). Family caregiving appears to be similar to other prosocial helping behaviors in that it provides stress-buffering adaptations that ameliorate the impact of stress on major health outcomes such as mortality. (PsycINFO Database RecordĀ