Psychological trauma can occur when a person experiences an extreme stressor that negatively affects his or her emotional or physical well-being. Trauma can cause emotionally painful and distressing feelings that overwhelm a person’s capacity to cope and leave him or her with feelings of helplessness. Traumatic events can lead to Posttraumatic stress disorder (PTSD) and myriad other reactions, such as depression, substance abuse, sleep problems, and potentially chronic health problems, such as heart disease, diabetes, and cancer. Trauma exposure cuts across all walks of life, regardless of age, race, ethnicity, socioeconomic status, religion, and cultural background. The types of traumatic events includes child maltreatment, intimate partner violence/domestic violence, rape or sexual violence, military sexual trauma, sex trafficking, combat-related trauma, civilian war trauma and torture, disasters, serious accidents, and life-threatening medical illness. This book provides an overview of the rich and varied research conducted on psychological trauma over the past 3 decades.