This book brings together the most recent empirical developments in learning theory for understanding the etiology and treatment of fears and phobias. The editors have assembled contributions from leading scientists whose work represents the cutting edge in such areas as measurement methodology, neurobiology, cognitive processing, behavioral models, emotion regulation, and pharmacological and other clinical treatments. After a review of the history of fear learning and basic concepts and methods in fear measurement, subsequent chapters elucidate processes of acquisition and maintenance of fear, finally moving to the extinction, renewal, and reinstatement of fear. The research synthesized in this book has applicability to the entire spectrum of anxiety disorders, including obsessive-compulsive disorder, social anxiety disorder, and specific phobias.