This chapter considers the various postdisaster social dynamics in considerable depth, with particular focus on social support. Social support is most often referred to as social interactions that provide individuals with actual assistance and embed them into a web of social relationships perceived to be loving, caring, and readily available in times of need. The chapter summarizes existing empirical research on the mobilization of support in the aftermath of disasters; this is the research that descends most directly from the early observations of Kutak, Fritz, Barton, and other disaster sociologists. The chapter also summarizes research on deterioration of support in the aftermath of disasters, an observation that emerged later in disaster studies, but just as prominently, that sense of community was sometimes destroyed by catastrophic events. It describes the impact of received and perceived social support on the mental health of disaster survivors.