On November 13, 2015, the attacks in Paris and Saint-Denis, carried out by three Islamist commandos and claimed by ISIS, were the deadliest in France since the end of World War II. In the months that followed, the November 13 Program was launched by the CNRS and Inserm to study the construction of individual and collective memory around an event that profoundly marked French society. Today, the testimonies of 27 volunteers—among some 1,000 people—who participated in the study form a mosaic of experiences that shows how trauma extends beyond the immediate circle to permeate the national collective memory.