Abstract
This chapter reviews the literature on the association between traumatic stress exposure and rates of both posttraumatic stress disorder (PTSD) and acute stress disorder (ASD) among children and adults. It begins by reviewing current definitions of PTSD and ASD, which vary substantially across diagnostic systems. The chapter highlights research linking large-scale events, such as natural disasters and acts of terrorism, with the emergence of PTSD and ASD, as well as the literature on the impact of individual traumatic events, such as sexual assault, child sexual abuse, and medical trauma. The chapter concludes by noting several important directions for future research in the area of trauma exposure and traumatic stress.