Bessel A. van der Kolk, M.D., is Director of the Trauma Center at Human Resources Institute in Boston Massachusetts, a center for the treatment and study of traumatized children and adults. He is an Associate Professor of psychiatry at Harvard Medical School and the past President of the International Society of Traumatic Stress Studies. He has done extensive research on developmental and biological aspects of the human adaptation to trauma, including studying the nature of traumatic memories. He was co-principal investigator for the DSM-IV Field Trial for PTSD. He is the author of two previous books on the human response to trauma:PTSD: Psychological and Biological Sequelae(1984) andPsychological Trauma,(APA Press, 1987). Lars Weisaeth, M.D., Ph.D., is Professor of Disaster Psychiatry at the University of Oslo, Norway, and frequent consultant to the United Nations and other international organizations regarding approaches to treating traumatized civilians and soldiers. Alexander C. McFarlane is Professor of Psychiatry at the University of Adelaide and Head of the Department of Psychiatry at the Queen Elizabeth Hospital in South Australia. His research in the field of trauma is wide ranging and began following a large bushfire disaster which affected his community in 1983. His clinical work is with victims of a variety of traumas, including accidents, disasters, torture, and war.