Book excerpt: Trauma is defined as a sudden, potentially deadly experience, often leaving lasting, troubling memories. Traumatology (the study of trauma, its effects, and methods to modify effects) is exploding in terms of published works and expanding in terms of scope. Originally a narrow specialty within emergency medicine, the field now extends to trauma psychology, military psychiatry and behavioral health, post-traumatic stress and stress disorders, trauma social work, disaster mental health, and, most recently, the subfield of history and trauma, with sociohistorical examination of long-term effects and meanings of major traumas experienced by whole communities and nations, both natural (Pompeii, Hurricane Katrina) and man-made (the Holocaust, 9/11). One reason for this expansion involves important scientific breakthroughs in detecting the neurobiology of trauma that is connecting biology with human behavior, which in turn, is applicable to all fields involving human thought and response, including but not limited to psychiatry, medicine and the health sciences, the social and behavioral sciences, the humanities, and law. Researchers within these fields and more can contribute to a universal understanding of immediate and long-term consequences–both good and bad–of trauma, both for individuals and for broader communities and institutions. Trauma encyclopedias published to date all center around psychological trauma and its emotional effects on the individual as a disabling or mental disorder requiring mental health services. This element is vital and has benefited from scientific and professional breakthroughs in theory, research, and applications. Our encyclopedia certainly will cover this central element, but our expanded conceptualization will include the other disciplines and will move beyond the individual.