Among the commemorations that marked the tenth anniversary of the terrorist attacks of September 11th was held the conference “September 11th-12th, the Individual and the State Faced with Terrorism” (French Embassy in Washington D.C. April 11th and 12th, 2011). This new trans-Atlantic chapter of the program “Memory and Memorialization” (Partner University Fund) was original in three ways : A transdisciplinary approach, calling to speak specialists in neuroscience, psychoanalysis, psychiatry, history, but also legal experts, law historians, even political science and public policy specialists ; An approach at once retrospective and projective : September 11th is calling upon the competence of social as well as legal historians. Because the terrorist act concerns as well its author as its victim, the experience of psychological development of trauma specialists is also necessary. Projecting out to the future, it is important to discover the society’s reaction to terrorism and the curative possibilities discovered by neuroscience ; An approach with a growing focus : the personal construction of the victim, whose trauma ends, thanks to various cerebral dynamics, is coming as a first level. Construction via intermediation is the second level, bridging the gap between the individual and his/her society. Lawmakers try to codify damages relative to the suffering endured, indemnization measures are adopted, and incriminations changed. As a third level, collective construction, by the big narrative that shapes our understanding of the event, and finally by the State itself that crafts its own memory.