This chapter describes evolving patterns of drug misuse in sport, and reciprocal systems for defining and detecting doping, across the late twentieth century. The International Olympic Committee's list of prohibited substances and methods is presented as a primary tool for developing and administering such systems. Developments in the list since its introduction have been stimulated both by increasingly sophisticated detection methods, and by the imperative to recognise and anticipate trends in doping. The historical argument that doping is incompatible with the ethical nature of sport, and relates to pressures and inducements to misuse drugs, particularly at the élite level, is also addressed. Finally, recent developments in international collaboration between governments and the sporting community are covered, and continued efforts to harmonize standards in anti-doping policies and practices are advocated.