Could the acute stress of a traumatic event actually promote psychological health? Previous research has focused almost exclusively on the potential of traumatic experiences to initiate a process of posttraumatic growth (Tedeschi & Calhoun, 2004). However, the possibility that people can experience psychological improvement-a reduction in preexisting distress-as a direct consequence of a traumatic event has been ignored, perhaps understandably. Indeed, on its face, the prospect seems absurd. Yet a growing literature has documented that stressful experiences, as well as painful ones, promote various beneficial social outcomes. For example, inducing stress in a laboratory increases trust, trustworthiness, and sharing behavior (von Dawans, Fischbacher, Kirschbaum, Fehr, & Heinrichs, 2012) and also improves social cognition (Smeets, Dziobek, & Wolf, 2009). Furthermore, painful experiences, when shared with others, can serve as "social glue," prompting a greater sense of solidarity and bonding (Bastian, Jetten, & Ferris, 2014). These controlled laboratory experiments dovetail with a considerable literature on the aftermath of mass traumas. After such events, there is a collective and immediate outpouring of support, both emotional and material, to help survivors cope with the disaster (Norris et al., 2002; Solnit, 2009). These effects, well documented in the historical and sociological literatures, have been variously described as a "post-disaster utopia" (Wolfenstein, 1957), "a paradise built in hell" (Solnit, 2009), and a "city of comrades" (Prince, 1920). Consistent with laboratory research, postdisaster communities have been characterized by a high degree of internal solidarity, an increase in