This dissertation investigates the multiple grammars of trauma, survival, and witnessing through which personal suffering was articulated and acted upon in the aftermath of November 13, when a series of attacks on the Bataclan theater, cafés in Paris, and the Stade de France in Saint-Denis left 131 dead and thousands of survivors. Based on four years of participant observation research and original archival scholarship in France between 2018 and 2022, this research brings ethnology and history together to examine the aftereffects of colonialism not only “far afield” but also—within an epistemological frame that foregrounds relationality—at the diasporic “center.” “Postmetropolitan Trauma,” as I term it, thus offers a novel approach to the history of our present. Following the 2015 attacks in France, state insurers are processing individuals claims for PTSD compensation from the Guarantee Fund for Victims of Acts of Terrorism (FGTI). Meanwhile, an adjacent diagnostic practice is taking place at the National Institute of Health and Medical Research, where neuropsychologists are conducting biomedical research on PTSD in survivors. As testimonies are being processed by FGTI for financial compensation, on the one hand, and for a science of memory, on the other, a paradox arises: The ideal survivor for the neuropsychologist is she who overcomes her PTSD, and yet, for the purposes of trauma compensation, that is, from a forensic point of view, the survivor must remain symptomatic. In analyzing this paradox, I uncover reparation as a dynamic process of community making which is wider than its result, the final awarding or denial of compensation. While studies of the “War on Terror” have focused on the rise of the terrorist as the new Other, “Postmetropolitan Trauma” instead centers on the processes of subjectivation, identity construction, and community making that compensation produce in the wake of November-13. Who is considered a “survivor,” and as such an insider to trauma, and who is denied compensation as a “mere” witness? This novel approach reveals that the themes of violence and belonging are not restricted to the construction of perpetrators alone, but also shape the treatment of victims. In so doing, the dissertation proposes a new model for understanding the contradictory impulses of inclusion and exclusion, of violence and care, that shape the making of moral communities through historical trauma.