Several researchers have identified social capital as a means to improve the social sustainability of communities. While there have been many studies investigating the benefits of social capital in homogeneous White communities, few have examined it in Black homogeneous communities. Also, there has been limited research on the influence of racism on social capital in African American communities. In this dissertation a comparative case study was used within a critical race theory framework. The purpose was to explore the role of racial oppression in shaping social capital in majority African American communities. Data were collected from 2 majority Black communities in Florida. The collected data included reviews of local news reports, voter turnout reports, and community health assessments, along with focus groups and semi structured interviews with a purposive sample of 20 of the communities' African American residents. Benet's polarities of democracy model was employed to analyze the relationship between racism and social capital. Analysis included inductive coding followed by pattern matching to identify overarching themes between the selected cases. One key theme was that perceived racial disparity inhibited bridging and linking social capital in the selected communities. Another key theme was that racism created social capital deficiencies and a dysfunctional community culture, which limited the capacity to address collective issues. Social change implications include specific policy recommendations to state and local leaders to increase the participation of Black community members in democratic processes. Additionally, this research has potential to improve understanding of the various ways that racism may affect Black Communities.