A significant barrier to understanding the psycho-social antecedents of doping use among adolescent athletes is the lack of valid measures. In order to address this issue, the first aim of this paper was to develop and validate the Adolescent Sport Doping Inventory (ASDI) among adolescent athletes from Asia, Europe, North America, and Oceania. The second aim was to assess the construct validity of the ASDI. As such, this paper is divided into two parts. Part 1 relates to the development of the ASDI and contains two studies: Item Development (Study 1) and Factorial Validity (Study 2). Part 2 contains information on how the psycho-social variables measured in the ASDI are associated with situational temptation, and honesty (Study 3), maturation (Study 4), stress and coping (Study 5), and coaching (Study 6). In devising the ASDI, 19 different models were examined, which culminated in a 9-factor, 43-item ASDI. Coping, mastery-approach goals, and cognitive-social maturity were associated with doping attitudes. Caring motivational climates, strong coach-athlete relationships, and positive coach behaviors were associated with athletes being less susceptible towards doping, which provides construct validity for the ASDI. The ASDI is a valid tool to assess the psycho-social factors associated with doping among adolescent athletes. This questionnaire can be used to identify athletes who are the most at risk of doping, assess how the psycho-social factors associated with doping change over time, and to monitor the impact of anti-doping interventions for adolescent athletes.