The development of social capital in young people is positively associated with educational attainment, achievement, and psychosocial factors. Prior research has explored factors that contribute to social capital, such as offline social networks. To a lesser extent, studies have analyzed the relationship between online social networks and students' social capital. However, educational researchers have yet to examine this relationship among students from low-income families. It is especially important to consider low-income students since historically they have not reached the same educational attainment and achievement levels as their higher income peers. In this article, we conduct a regression analysis on survey responses from high school students from low-income families (n = 607) to examine the relationship between intensity of online social network site use, social capital, and other measures of psychological well-being. Results suggest positive associations between use of online social network sites and two forms of social capital. Qualitative data were also utilized to illuminate low income students' opportunities or barriers for forging and sustaining relationships through online social network sites and implications for future research and education are discussed. (Contains 7 tables and 1 footnote.)