Optimism is associated with reduced mortality risk among Whites, but evidence for this relationship is limited among African-Americans, whose life expectancy is shorter than Whites. This study examined the association between optimism and mortality rate in African-Americans. Data were from African-American women (n = 2652) and men (n = 1444) in the United States from the Jackson Heart Study. Optimism was measured using the Life Orientation Test-Revised at the baseline period (2000-2004), and mortality data were obtained until 2018. Using Cox proportional hazards models, we estimated hazard ratios (HRs) of mortality by optimism level, controlling for sociodemographic factors, depressive symptoms, health conditions, and health behaviors. In secondary analyses, we evaluated potential effect modification by sex, age, income, and education. Higher optimism was related to lower mortality rates (HR = 0.85, 95% confidence interval [CI] = 0.74, 0.99), controlling for sociodemographic factors and depressive symptoms. After further adjusting for health conditions and health behaviors, associations were slightly attenuated (HR = 0.89; 95%CI = 0.77, 1.02). Stronger associations between optimism and mortality were observed in men, among those with higher income or education, and with age ≤ 55 (all p's for interaction terms <0.06). In summary, optimism was associated with lower mortality rates among African-Americans in the Jackson Heart Study. Effect modification by sociodemographic factors should be further explored in additional research considering optimism and mortality in diverse populations. Positive factors, such as optimism, may provide important health assets that can complement ongoing public health efforts to reduce health disparities, which have traditionally focused primarily on risk factors.