This dissertation presents three empirical studies on the distribution and role of social capital among immigrants in the United States. Using data from two national datasets - the New Immigrant Survey (NIS 2003, 2007) and the Social Capital Community Benchmark Survey (SCCBS 2000) - it examines the implications of social capital for immigrants' social and economic integration. In doing so, it addresses several key limitations within migration research. The first limitation it addresses is the focus of prior research on migrants' co-ethnic (bonding) social capital and the limited research on immigrants' "bridging" social capital and distributional inequities across immigrant groups. Second, while most research has focused on role of social capital in economic integration, relatively little is known about the short-run and long-term implications of immigrants' social capital for their health and well-being. Third, prior research has generally focused on specific immigrant groups, particularly Hispanic and Asian immigrants, and it is unclear if prior findings are generalizable to immigrants overall or if they are simply capturing group and/or context-specific effects of social capital. This dissertation includes three studies that provide pieces of evidence that address these limitations and contribute to the migration literature. In the first study, I explore the link between race, immigration status and social network diversity. Using data on personal network characteristics from the SCCBS (2000), I examine the role of race and immigration status in the distribution of ethnicity and status-bridging social capital. Findings confirm the double disadvantage of minority and outsider status for minority immigrants when it comes to access to network diversity, which is to say group (i.e. race) differences in native-immigrant gaps in access to ethnicity-bridging social capital.