Arnold M. Washton, PhD, is an addiction psychologist in private practice in New York City (Recovery Options) and Princeton, New Jersey (The Washton Group). A specialist in the treatment of substance use and other behavioral health problems since 1975, Dr. Washton has served on the faculty in Psychiatry at New York University School of Medicine and on the voluntary staff of the University Medical Center at Princeton. He was the founding president of the Division on Addictions of the New York State Psychological Association and has served on advisory boards for the U.S. Food and Drug Administration and special committees of the U.S. Senate, the U.S. House of Representatives, and the American Psychological Association. Dr. Washton's clinical work, teaching activities, and publications have often focused on integrating the principles and practices of client-centered psychotherapy into the treatment of addictions.

Joan E. Zweben, PhD, is a clinical psychologist with over 35 years of experience in treating addiction and in training treatment practitioners. These practitioners include peer counselors, social workers, marriage and family counselors, psychologists, criminal justice personnel, nurses, and physicians. She has a broad-based background in treatment of both alcoholism and drug dependence and has experience with both residential and outpatient modalities. She has served on numerous work groups focused on policy issues. Dr. Zweben is the founder and Executive Director of the 14th Street Clinic (1979-2007) and the East Bay Community Recovery Project (1989-present). Through these organizations, she has collaborated with researchers locally and nationally since 1981. She is the author of 4 books and over 55 articles or book chapters and editor of 15 monographs on treating addiction.