The 'insider-outsider problem' has had little impact on the study of religion in preChristian Rome. Classicists generally assume that the modern idea of sacrice as the ritual killing of an animal applies to the Roman context. This study argues, however, that the apparent continuity is illusory in some important ways and that we have lost sight of some ne distinctions that the Romans made among the rituals they performed. Sacricium included vegetal and inedible offerings, and it was not the only Roman ritual that had living victims. Roman sacricium is both less and more than the typical etic notion of sacrice.Keywords: sacrice; Rome; emic; etic; pollucere; mactare I Those working in the social sciences have, for some time, been wrestling with the 'insider-outsider problem': how can one person genuinely understand the thoughts, beliefs, and actions of another? Insiders can report their own subjective experience, but very often this diverges from the assessments of those observing from the outside, from what is perceived as a more objective position. The problem was cleverly illustrated in a classic article that is standard reading for introductory anthropology and religious studies courses but that is generally unfamiliar to classicists, entitled 'Body rituals of the Nacirema' by the anthropologist Horace Miner. The article offers a brief account of the daily habits of this North American tribe whose members place a great deal of emphasis on maintaining and improving the body, for example:The fundamental belief underlying the whole system appears to be that the human body is ugly and that its natural tendency is to debility and disease. Incarcerated in such a body, man's only hope is to avert these characteristics through the use of the powerful inuences of ritual and ceremony. Every household has one or more shrines devoted to this purpose. The more powerful individuals in the society have several shrines in their houses and, in fact, the opulence of a house is often referred to in terms of the number of such ritual centers it possesses. Most houses are of wattle and daub construction, but the shrine rooms of the more wealthy are walled with stone. Poorer families imitate the rich by applying pottery plaques to their shrine walls. 1 * I owe many thanks to C. P. Mann, B. Nongbri, and J. N. Dillon for their thoughtful, challenging responses to earlier drafts of this article, and to audiences at Trinity College, Baylor University, and Bryn Mawr College for comments on an oral version of it. J. B. Rives provided valuable consultation on specic points and V. C. Moses generously shared her work-in-progress on the osteoarchaeological evidence from S. Omobono. I also thank the anonymous reviewers for helpful comments, suggestions and objections that have greatly improved this piece. I have tried to respond to them all. The errors and aws that remain are all my own.