Most historians, epidemiologists, and physicians credit the Framing-ham Heart Study for introducing the term "risk factor" to public health and medicine. Many add that the term came from life insurance companies. This familiar history is incorrect. Taking advantage of the expanding availability of digitized and full-text searchable journals, textbooks, newspapers, and other sources, we have uncovered a deeper and broader history. Antecedent concepts (such as risk, factor, predisposition) have ancient roots. "Risk factor" began to appear in the late 19th and early 20th centuries in many industries, not just in insurance but also in finance, agriculture, and manufacturing. The term appeared in the occupational health literature in 1922. It reappeared in the 1950s in many different areas of medicine including psychiatry, surgery, cardiology, epidemiology, and aerospace medicine. Furthermore, despite the influential appearance of "risk factor" in a 1961 Framingham Heart Study publication, the term did not gain momentum in medicine and public health until the mid-1970s. While our analysis is not exhaustive, our findings are extensive enough to require a substantial revision to the history of the risk factor.