Forbidden Knowledge: Medicine, Science, and Censorship in Early Modern Italy examines the Catholic censorship of medical books to reevaluate the classic narrative of a Galilean struggle between faith and science. This study of censors and scholars, books and libraries, and above all the contested status of scientific knowledge reveals the complex interplay between efforts at intellectual control and the demand for prohibited knowledge in Counter-Reformation Europe. The archive that Catholic censorship created—populated with letters, bureaucratic records, censor’s reports, reading licenses, and even expurgated books themselves—repeatedly invokes the utility of medicine and medical literature as a justification for making books selectively available to readers. This discourse about the utility of knowledge arose out of negotiations over the status of forbidden medical knowledge and would become an essential feature of discussions about new and controversial scientific developments. The Catholic Church developed a process of intellectual control that ultimately highlighted the ambiguities, contradictions, and paradoxes of censorship. This study opens a window for understanding the rich and complicated relationships between physicians and the Church, medicine and science, readers and their books, and the utility of knowledge in the world of early modern learning.