From the published literature of the 1950s, the social history of anti-substitution law is analyzed in terms of sociological theory on the construction of social problems. The analysis reveals how the substitution of generic drugs for prescribed brands came to be recognized as a social problem in need of remedial legislation. The most influential party in the process was the brand-drug industry which centered the debate on matters of public health and professionalism instead of industrial profitability. The industry was able to form a coalition of interests and establish the saliency and legitimacy of the problem, even though there was no objective evidence to establish brand substitution as a hazard to health. The case fits well into the theory of social problem construction. Other issues in health care, particularly drug issues can be studied from this same perspective.