Racial disparities in many age-related health outcomes, including cognitive and functional impairment, are persistent and pervasive among older Americans. The weathering framework, a well-supported explanation for racial disparities in aging, posits that impacts of racism lead to accelerated biological aging for Black relative to White Americans. Research investigating the specific exposures and biological mechanisms that contribute to weathering and its consequences for cognitive and functional health is needed to inform strategies to eliminate these disparities. In this dissertation, I use epigenetic aging as a measure of weathering and hypothesize that it is an important biological intermediate between social factors (i.e. socioeconomic status, neighborhood socioeconomic deprivation, air pollution, and perceptions of neighborhood stressors) and age-related outcomes (i.e. cognitive and functional performance and decline). I perform retrospective quantitative analyses of data from non-Hispanic Black and White adults 50 years and older in the Health and Retirement Study whose 2016 epigenetic age is linked to survey data and to neighborhood exposures based on residential location. I use two measures of epigenetic aging based on DNA methylation which are robust measures of weathering. Outcomes are cognitive test scores at baseline and change over two years, and prevalence and incidence of instrumental activity limitations. Results show accelerated epigenetic aging for Black participants compared to White. Higher neighborhood deprivation and greater risk from fine particulate matter pollution exposure for Black participants significantly contribute to the disparity in epigenetic aging. Epigenetic aging is associated with and contributes to racial disparities in cognitive and functional performance and decline. Individual socioeconomic status plays a large role in these associations, accounting for substantial portions of the disparities in both epigenetic aging and cognitive and functional outcomes. These results support the weathering framework and the role of epigenetic aging as an important intermediate between social drivers of health, which are shaped by racism, and racial disparities in age-related outcomes. This work has implications for future research and policy to further health equity and racial justice.