The distinctively Shiʿi conception of non-Muslims as bearers of a contagious form of impurity emerges gradually, reaching its classical form only in the 5th/11th century. Contrary to common scholarly presumptions, Q. 9.28 does not constitute the point of origin for this conception but rather serves as retroactive justification for its validity. This essay utilizes ḥadīth collections and works of law from the 2nd/8th through 5th/11th centuries to trace the emergence of Shiʿi notions regarding the impurity of non-Muslims and the parallel emergence of distinctively Shiʿi norms regarding the meat of animals slaughtered by non-Muslims. It concludes by suggesting that the differences between Sunni and Shiʿi notions regarding the food and impurity of non-Muslims reflect the different ways in which Sunnis and Shiʿi conceive of the Islamic community itself.