Gerard J. Connors, PhD, is Director of the Research Institute on Addictions at the University at Buffalo, State University of New York. Coauthor of a textbook on drug use and abuse, Dr. Connors has published over 100 scientific articles and book chapters in the area of alcoholism and addictive behaviors. Dennis M. Donovan, PhD, is Director of the Alcohol and Drug Abuse Institute at the University of Washington, where he is also Professor in the Department of Psychiatry and Behavioral Sciences and Adjunct Professor in the Department of Psychology. His more than 120 publications include Assessment of Addictive Behaviors (coedited with G. Alan Marlatt) and Changing Addictive Behavior (coedited with Jalie A. Tucker and G. Alan Marlatt). Carlo C. DiClemente, PhD, is Professor and Chair of the Department of Psychology at the University of Maryland, Baltimore County. Dr. DiClemente is the codeveloper of the stages-of-change model with James Prochaska. He has authored numerous scientific articles, books, and book chapters examining the process of human behavior change and the application of this model in a variety of problem behaviors. His recent publications include Group Treatment for Substance Abuse: A Stages-of-Change Therapy Manual (coauthored with Mary Marden Velasquez et al.).