MICHEL HERSEN, PHD, ABPP, is Professor and Dean of the School of Professional Psychology at Pacific University in Forest Grove, Oregon, and past president of the Association for Advancement of Behavior Therapy. He is coauthor and coeditor of 146 books and author of 226 scientific journal articles.SAMUEL M. TURNER, PHD, ABPP, was Professor and Director of Clinical Training in the Psychology Department at the University of Maryland and codirector of the Maryland Center for Anxiety Disorders.DEBORAH C. BEIDEL, PHD, ABPP, is Professor of Psychiatry, Director of Research in Child Psychiatry, and Director of the Anxiety, Stress, and Trauma Division, Department of Psychiatry, Penn State College of… Medicine. She is the author or coauthor of over 200 journal articles, book chapters, and books.