Post-Traumatic Stress Disorder (PTSD) in children and adolescents occurs when a child is exposed to one or more events that are unexpected, uncontrollable, life-threatening, and likely to cause serious harm or injury to himself/herself or someone significantly important to the child. In response, the child experiences fear, hopelessness, or horror and responds with a characteristic set of physiological and psychological reactions, which perpetuates the overwhelming and confusing feelings. Symptoms are characterized into three groups: persistent, intrusive re-experiencing of traumatic recollections; avoidance of reminders/numbing; and increased arousal.