Disaster scholars’ interest in social capital has grown dramatically, due in part because social capital gets at the heart of collective action, cooperation, and the therapeutic community that occurs during emergencies. While social capital has been highlighted as a positive factor for communities under extreme events, questions remain. This chapter reviews how social capital is conceptualized and operationalized in disaster research and the current state of knowledge on this topic. The chapter begins with social capital theory. Next, the relevant research on social capital in disaster is reviewed. This research is categorized by unit of analysis (individual or collective) and the phase of disaster (mitigation, preparedness, response, and recovery). Finally, this chapter concludes with a critical assessment of the use of social capital by disaster scholars and offers implications for future research.