Synopsis Abnormal psychology can broadly be defined as the application of the principles of psychology research into the causes and treatment of psychopathologies. The central and most controversial aspect of abnormal psychology is the issue surrounding the meaning of the term ’abnormal’. In other words, what precisely constitutes an abnormal psychological state? There is no single and conclusive view of what is ‘abnormal’ and each theoretical approach is determined by underlying assumptions about the meaning of this term. Abnormal psychology studies the nature of psychopathology, its causes, and its treatments. Abnormal Psychology gives students the opportunity to explore the latest theories a nd research in our ever-changing search for answers to the complex questions of psychopathology. The editor invites students to search for clues, follow-up on hunches, evaluate evidence, and participate in a process of discovery as they sift through the evidence on the origins of psychopathology and the effectiveness of specific interventions.