ABSTRACT This article addresses contamination within anti-doping as a scientifically complex and politically critical source of ignorance, representing a threat to the World Anti-Doping Agency’s (WADA) credibility. Contamination can be described as any situation in which athletes come in contact with prohibited substances through their environment, without their fault, and is an unknown looming over athletes and anti-doping organisations alike. Dealing with contamination is a vital stake for WADA as the phenomenon jeopardises institutional features of anti-doping, including the strict liability principle whereby athletes are deemed responsible for whatever is present in their body. Building on studies of ignorance in organisations, this article draws from frame analysis to apprehend WADA’s policy response to contamination. Through WADA Minutes and other releases over the period 2000–2023, we analyse how WADA handles and justifies shifts in its framing of contamination towards its global audiences. Our results show that organisational attitude towards ignorance is a dynamic process. This process intertwines with the organisation’s need to maintain its credibility, especially where elucidating the issue threatens components constitutive of its community’s cosmology as defined by Goffman. The concept of ‘frame consistency’ illuminates how this requires the organisation to retain the community’s trust by convincing them that its framing remains coherent over time and that the policy issue can be mastered without undermining the system’s overarching principles. To achieve these goals, WADA mobilises techniques of impression management, also relying on the institutions of science and the law as guardians of its cosmology.