Several different theories have been presented to explain the relationship between childhood abuse and adult vulnerability to post-traumatic stress disorder (PTSD). Some of these explanations suggest that either adult attachment or dissociation as the mediating variable is not necessarily exclusive and that both mediate the relations between childhood abuse and the emergence of PTSD in adulthood. This study examined the etiology of PTSD through the study of 284 adults from the New York metropolitan area who witnessed the terrorist attack on the World Trade Center on September 11, 2001. The study tested two hypotheses: (1) individuals reporting histories of childhood sexual abuse (CSA) and/or childhood physical abuse (CPA) would experience more severe symptoms of PTSD in response to the terrorist attack of September 11th and (2) individuals who witnessed the attack live would endorse more symptoms of PTSD than those who witnessed it via delayed broadcasting. It also hypothesized that the quality of one’s adult attachments and the extent of one’s tendency towards dissociation would mediate the relationships between childhood abuse and symptoms of PTSD. The results supported the relationship posited to exist between childhood abuse and the emergence of PTSD in adulthood and the association between childhood abuse and adult attachment quality and dissociative tendencies. Study limitations are presented and discussed. Tables and references