ABSTRACT The Adolescent Sport Doping Inventory (ASDI; [Nicholls, A. R., Levy, A. R., Meir, R., Sanctuary, C., Jones, L., Baghurst, T., Thompson, M. A., & Perry, J. L. (2019). The development and validation of the adolescent sport drug inventory (ASDI) among athletes from four continents. Psychological Assessment, 31(11), 1279–1293. https://doi.org/10.1037/pas0000750] was one of the first questionnaires designed specifically to measure psycho-social doping constructs among adolescent athletes. Little is known about the reliability of this scale, and nor the stability of the psychosocial variables that the ASDI assesses. The aim of this paper was to assess the reliability of the ASDI, along with the extent to which key psychosocial constructs are stable, and whether there was variance across four clusters. Three independent samples of athletes were recruited. Athletes completed the ASDI one week apart (Sample 1, 92 athletes), 8 weeks apart (Sample 2, 134 athletes), and 16 weeks apart (Sample 3, 86 athletes). Findings revealed that the ASDI is a robust and reliable measure. While there was little within-subject variance in the data assessed one week apart (Sample 1) and 8 weeks apart (Sample 2), correlation coefficients in Sample 3 were markedly lower than Samples 1 or 2. The data also revealed that there was movement between cluster profiles for the eight- and 16-week gap, but not the one-week gap. In the short-term, psychosocial variables such as attitudes doping and susceptibility towards doping are relatively stable among adolescent athletes, although there is some movement between doping clusters. This could infer that ongoing anti-doping education is required to prevent undesirable changes in these important factors on a regular basis within adolescence.