Russell A. Barkley, PhD, ABPP, ABCN, before retiring in 2021, served on the faculties of the University of Massachusetts Medical Center, the Medical University of South Carolina, and Virginia Commonwealth University. 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, includingTaking Charge of ADHDandYour Defiant Child. He has also published six assessment scales and more than 300 scientific articles and book chapters on attention-deficit/hyperactivity disorder, executive functioning, and childhood defiance. 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 iswww.russellbarkley.org.