Michel Hersen (Ph.D., ABPP, State University of New York at Buffalo, 1966) is Professor and Dean of the School of?Professional Psychology?at Pacific University. He is?Past President of the Association for Advancement of Behavior Therapy.? He has coauthored and co-edited 146 books and has published 225 scientific journal articles. He is co-editor of several psychological journals, including Behavior Modification, Aggression & Violent Behavior: A Review Journal, Clinical Psychology Review, and Journal of Family Violence.?He is Editor-in-Chief of the Journal of Anxiety Disorders and of Clinical Case Studies. Earlier in his career, he was in full-time private practice and on several occasions he has had part-time private practices. Peter Sturmey (BSc., PhD. M/Clin Psychology A.F. B. Ps.S University of Liverpool, UK)?is Professor in the Department of Psychology, Queen's College, City University of New York. He is recognized as an international authority on functional assessment, and published Functional Analysis in Clinical Psychology with Wiley in 1996. More recently, he co-edited Offenders with Developmental Disabilities with Bill Lindsay and John Taylor in 2004.