U.S. working mothers experience frequent daily hassles, yet little is known about how working mothers have disproportionate abilities to handle stress. The purpose of this cross-sectional study was to determine the extent to which coping self-efficacy mediated the effect that cumulative daily hassles had on working mothers' health outcomes (i.e., physical functioning, role-physical, bodily pain, general health, vitality, social functioning, role-emotional, and mental health). The transactional model of stress and coping, social cognitive theory, and self-efficacy theory provided the theoretical foundations for this study. Daily hassles were used for this study as an additional theoretical approach for measuring stress. A total of 235 working mothers completed the Daily Hassles Scale, Coping Self-Efficacy Scale, and Short Form 36 version 2 (SF-36v2) on a secure online website. The respondents reported moderate confidence in their abilities to cope with life despite experiencing an average of 44 daily hassles per month. Simple regressions confirmed repeated exposure to daily hassles was significantly associated with reduced coping self-efficacy and health outcomes. Mediation with multiple regression analysis revealed that coping self-efficacy partially mediated the relationship between cumulative daily hassles and health outcomes, suggesting coping self-efficacy was a protective psychosocial factor for working mothers. This study contributes to positive social change by aiding practitioners in identifying protective psychosocial factors and helping working mothers to implement the findings with the intention of reducing daily hassles and improving health outcomes.