Retrospective and prospective studies consistently show that individuals exposed to human-generated traumatic events carry a higher risk of developing Posttraumatic Stress Disorder (PTSD) than those exposed to other kinds of events. These studies also consistently identify perceptions of social support both before and after a traumatic event as an important factor in the determining vulnerability to the development of PTSD. We review the literature on interpersonal traumas, social support and risk for PTSD and integrate findings with recent advances in developmental psychopathology, attachment theory and social neuroscience. We propose and gather evidence for what we term the social ecology of PTSD, a conceptual framework for understanding how both PTSD risk and recovery are highly dependent on social phenomena. We explore clinical implications of this conceptual framework.