DAVID A. CLARK, PhD, is Professor of Psychology at the Universityof New Brunswick. He has published over 50 scientific articles ondepression and anxiety, and has collaborated extensively with AaronT. Beck. AARON T. BECK, MD, DMS, is University Professor of Psychiatry atthe University of Pennsylvania. He has authored or coauthored 12books and 350 scientific articles on cognitive theory andtherapy. BRAD A. ALFORD, PhD, is Professor of Psychology at the Universityof Scranton. His previous book, coauthored with Aaron T. Beck, istitled The Integrative Power of Cognitive Therapy.