David A. Clark, PhD, L. Psych., is professor of psychology at the University of New Brunswick in Fredericton, NB. He has published numerous articles on cognitive theory and therapy of depression and obsessive-compulsive disorder and is a founding fellow of the Academy of Cognitive Therapy. He is coauthor of Scientific Foundations of Cognitive Theory and Therapy of Depression with Aaron Beck and Brad Alford, and he has recently published the Clark-Beck Obsessive Compulsive Inventory with the Psychological Corporation. He has received a number of research grants to study the cognitive basis of distress. He is also an active member of the Obsessive-Compulsive Cognitions Working Group and is associate editor of Cognitive Therapy and Research.