Stephen Rollnick, PhD, is Honorary Distinguished Professor in the School of Medicine, Cardiff University, Wales, United Kingdom. He is a codeveloper of motivational interviewing, with a career in clinical psychology and academia that focused on how to improve conversations about change. He has worked in diverse fields, with special interests in mental health and long-term health conditions like diabetes, heart disease, and HIV/AIDS. Dr. Rollnick has published widely in scientific journals and has written many books on helping people to change behavior. He is coauthor (with William R. Miller) of the classic work Motivational Interviewing: Helping People Change, now in its third edition. He has traveled worldwide to train practitioners in many settings and cultures, and now works as a trainer and consultant in healthcare and sports.

William R. Miller, PhD, is Emeritus Distinguished Professor of Psychology and Psychiatry at the University of New Mexico, where he joined the faculty in 1976. He served as Director of Clinical Training for UNM's American Psychological Association-approved doctoral program in clinical psychology and as Codirector of UNM's Center on Alcoholism, Substance Abuse, and Addictions. Dr. Miller's publications include 35 books and more than 400 articles and chapters. He introduced the concept of motivational interviewing in a 1983 article. The Institute for Scientific Information names him as one of the world's most cited scientists.

Christopher C. Butler, MD, is Professor of Primary Care Medicine and head of the Department of Primary Care and Public Health at Cardiff University, UK. He trained in medicine at the University of Cape Town and in clinical epidemiology at the University of Toronto. For his doctoral work, under the direction of Stephen Rollnick, he developed and evaluated behavior change counseling and conducted qualitative research into patients' perceptions of advice against smoking from clinicians. Dr. Butler has published more than 70 papers, mainly on health behavior change and common infections. He has a general medical practice in a former coal-mining town in south Wales.