Objective: The purpose of this study was to investigate associations between financial hardship and change in emotional well-being-positive and negative affect-before to during the COVID-19 pandemic among middleaged and older Americans and to examine the extent to which associations were moderated by internal coping resources-dispositional mastery and optimism.Method: Data derived from the Leave-Behind Questionnaire in the 2016 and 2020 waves of the Health and Retirement Study, a nationally representative longitudinal survey of U.S. adults aged 51 and older (N = 1312). We estimated multivariate ordinary least squares regression models with interaction terms to evaluate prospectively the benefits of mastery and optimism as internal coping resources for middle-aged and older adults. Results: Dispositional mastery moderated the effects of financial hardship on changes in negative and positive affect, respectively, before to during the COVID-19 pandemic; however, optimism did not significantly moderate the effects of financial hardship on change in negative and positive affect before to during the COVID-19 pandemic.Conclusions: Our findings have implications for interventions aimed at improving middle-aged and older adults' emotional well-being by promoting internal coping resources. Specifically, interventions should focus on financial hardship and mastery for vulnerable middle-aged and older adults in the context of public health crises.