This article applies Robert Putnam's conception of social capital to the history of the Student Nonviolent Coordinating Committee (SNCC) in Mississippi during the 1960s. It challenges Putnam's privileging of bridging social capital at the expense of bonding social capital, arguing that such a binary interpretation fails to appreciate the extent to which bonding and bridging forms of social capital can work to reinforce each other. Putnam's inattention to the value of bonding social capital (particularly in the rigidly segregated South) means that he overestimates the importance of integration to grass-roots activism in the civil rights movement. The article emphasizes the fostering of intergenerational and inter-class links between activists and local people in the Mississippian African American community. It argues that SNCC's 1964 Mississippi Summer Project bequeathed a framework for African American political action in the state, even though the Project contributed to the demise of SNCC itself. Through this approach, it reveals the vast differences in the organizing style of the movement at a local and a national level, suggesting that the concept of social capital needs to be wielded with greater subtlety if it is to be used to analyse the civil rights movement.