Growing concerns about climate change, resource consumption, and waste have led policymakers and scholars to promote secondhand markets as key strategies to address environmental goals. Yet alongside the environmental benefits of reuse, there are often claims and suggestions that reuse participation can contribute to social capital. This chapter explores the relationship between reuse participation and social capital using both quantitative and qualitative methodologies, in an attempt to understand not just whether social capital is present in reuse economies, but what its impact is on those who participate. Drawing on a statewide household survey of reuse participation in Maine (n = 605), as well as interviews and participant observation with buyers, sellers, donors, and recipients of used goods (n = 54) we find that there are relationships between reuse and social capital. Our chapter ultimately argues that social capital and reuse are related, but that positive outcomes are not assured through participation in secondhand markets. Instead, we must understand social capital in all its complexity to create policies that achieve social, economic, and environmental well-being.