This paper examines the role of social capital -the set of supportive interpersonal interactions that exists in the family, community, and school -in promoting educational achievement. Employing data on public school students from the National Education Longitudinal Survey (NELS) and other secondary data sources, we examine the link between students' access to social capital and important educational benchmarks, especially standardized test scores for math and reading. Building on previous research, we attempt to refine the conceptualization and measurement of social capital. We then undertake a new exploration of test score gains realized by students over the course of the 8 th to 12 th grades in order to assess the extent to which social capital attributes of the family, school, and community contribute to such gains. Finally, we outline the implications of our findings in guiding education policy activities in rural America.