The psychiatric condition wherein a person who has witnessed or experienced an event which has caused mental trauma, and which leads to disturbing thoughts and feelings related to that event, is termed as post-traumatic stress disorder. The symptoms of PTSD can be broadly categorized into 4 types, namely, intrusion, avoidance, alterations in cognition and alterations in reactivity. Intrusion refers to recurrence of flashbacks and distressing dreams. Avoidance involves trying to avoid the places, people or situations which might remind an individual of the unpleasant memories. Alterations in cognition and mood cause the person to forget aspects of the trauma causing experience as well as distort feelings about themselves. This book contains some path-breaking studies on post-traumatic stress disorder and traumatic psychosis. It discusses the fundamentals as well as modern approaches of research within this field. This book is a collective contribution of a renowned group of international experts.