Though most physicians and public health officials deny that vaccination can cause autism, many autism parents believe there is such a link, and many of them resort to alternative treatments. This article takes no position on these controversies, but it uses the methods of reception history to explain how this “underground” movement has gained traction in the face of fierce opposition from the medical establishment and the mass media. The movement belongs to a long tradition of do-it-yourself medicine, which urged patients to read medical literature and treat themselves. Large-scale surveys of vaccine-hesitant websites and parents, and an intensive study of the reading done by six autism parents, reveals that these parents read extensively and critically both refereed medical literature and Internet postings by other autism parents. They are not “antiscience,” but they are producing and consuming literature about autism and interacting with each other on social media.