This entry reviews the definition and history of psychological trauma, some possible effects of psychological trauma (including posttraumatic stress disorder [PTSD] and resilience), treatment, and types of psychological trauma, including collective trauma, national trauma, intergenerational trauma, and international trauma.

Psychological trauma occurs when the human self-defense system becomes overwhelmed and disorganized. Trauma generally involves threats to life, bodily integrity, or psychological integrity; close personal encounters with violence and death; or sudden unexpected disruptions of affiliative bonds and individual frames of reference. Traumatic events are usually accompanied by feelings of intense fear, helplessness, loss of control, and threat of annihilation, which result in emotional, cognitive, and biological changes. The traumatic experience also concurrently depends on an identifiable objective occurrence and one's subjective interpretation and response.