Vassilis Barkoukis is an Assistant Professor of Teaching in Physical Education in the Department of Physical Education and Sport Science at the Aristotle University of Thessaloniki. His research interests involve the application of social cognitive approaches in physical education, physical activity and sports. He has authored several articles and book chapters on the psychological processes underlying doping use. He has participated in several international research projects on doping funded by the WADA, EU and other funding bodies. Lambros Lazuras is a Senior Lecturer in Psychology at the International Faculty of the University of Sheffield, and a research associate in the Department of Social and Developmental Psychology at ‘La Sapienza’ University of Rome. His research is focused on the social cognitive predictors of substance use and health-related behaviours. He has authored research articles, books, and chapters in edited books about doping use, and participated in several research projects about doping, funded by the World Anti-Doping Agency, and the European Commission. Haralambos Tsorbatzoudis is a Professor of Applied Sport Psychology in the Department of Physical Education and Sport Science at the Aristotle University of Thessaloniki. His research interests focus on the applications of social cognitive theories in sport and physical education. He has authored more than 100 articles in sport psychology, physical education and physical activity and has authored, translated and edited approximately 10 books relevant to psychology, education, research methods and sport science in Greek. He served as principal investigator in three WADA funded projects.