Eric J. Mash, PhD, is Professor of Psychology in the Department of Psychology and Program in Clinical Psychology at the University of Calgary. He is a fellow of the American and Canadian Psychological Associations; has served as an editor, editorial board member, and editorial consultant for many scientific and professional journals; and has written or edited numerous books and journal articles on children's mental health, child and adolescent psychopathology, child and adolescent psychotherapy, and child and family assessment. Dr. Mash's research has focused on family relationships across a variety of child and family disorders, including attention-deficit/hyperactivity disorder (ADHD), conduct problems, internalizing disorders, and maltreatment. Russell A. Barkley, PhD, ABPP, ABCN, is Clinical Professor of Psychiatry at the Virginia Treatment Center for Children and Virginia Commonwealth University School of Medicine. Dr. Barkley has worked with children, adolescents, and families since the 1970s and is the author of numerous bestselling books for both professionals and the public, including Taking Charge of ADHD and Your Defiant Child. He has also published five assessment scales and more than 275 scientific articles and book chapters on ADHD, executive functioning, and childhood defiance, and is editor of the newsletter The ADHD Report. A frequent conference presenter and speaker who is widely cited in the national media, Dr. Barkley is past president of the Section on Clinical Child Psychology (the former Division 12) of the American Psychological Association (APA), and of the International Society for Research in Child and Adolescent Psychopathology. He is a recipient of awards from the American Academy of Pediatrics and the APA, among other honors. His website is www.russellbarkley.org.