Description: The largest medical experiment involving human subjects occurred in the United States between April and June of 1954 when 1.6 million school-aged children lined up to receive an injection of an experimental polio serum. Why did parents knowingly and willingly present their children for this mass field trial? How do we explain this unprecedented consensus? Orthodox historiography points to panic and anxiety; that is, parents feared te disease so much they enthusiastically submitted their children as test subjects.This consensus argument, while compelling, only tells part of the story. An unexamined component is epistemological. Society had been medicalized. This had occurred on a large scale in popular culture, portraying scientists as heroes through the cinema for adults and comic books for children. A more significant formal and institutionalized approach involved the public schools. This took place at two levels. The first involved the creation of a medical structure through school inspections, medical examinations, and school nurses. Another layer of medicalization focused on instructing students in the benefits of personal hygiene, sanitation, and medical checkups. Classes in health education aimed at the social imperative of preventing illnesses and, failing that, treating them. Health education thus emphasized personal cleanliness, and utlimately peer acceptance and public welfare. During the first half of the twentieth century, in generation after generation, this legitimated medical professionals and institutions and built unqualified trust in the wisdom of science, setting the stage for the 1954 experiments. Methodology: This paper taps primary and secondary sources. The former includes health textbooks as well as oral histories of polios. The latter encompasses general literature in the history of medicine and education, and specifically focuses on a variety of works on the history of polio. Conclusions: This paper, by focusing on developments leading to the famous 1954 polio trials using schoolchildren, challenges orthodox historiography that explains the medicalization of education. This phenomenon proved to be broader and more pervasive than anxious parents and the mental hygiene model popular for the last three decades. Its roots reside as much in medical history as in educational history. The structure, involving visiting physicians and school nurses, grew out of the medical field. The subject matter, encompassing physicial education and health classes, emerged from the progressive education movement of the late nineteenth and early twentieth centuries. The culmination of these forces resulted in the most significant medical and educational event in American history.