Roman religion has conventionally been understood as a civic or “polis” religion in which the population performed the same rituals, attended the same festivals, and believed in the same divinities, an image conveyed by the extant Roman historians (including the Greek Polybius) and the antiquarian tradition. This convention has successfully obscured the fact that the range of religious activities in the City, to say nothing of the surrounding areas of central Italy, was in reality always far wider. More neutrally, we may view the religious field at Rome as a site of constant, if intermittent, conflict over effective means of relating to the other world and the legitimate use of religious knowledge, conflict that parallels in a different key the disputes over proper religious observance that took place within the ruling elite itself and its various priestly colleges. If the larger category of dismissal was superstition, the narrower and still more negative one was magical practice. There were however several sub-classes here, of which witchcraft and sorcery were but two. Over the thousand years of knowable Roman history, which saw a single city extend its political and extractive reach to a maximum of 4.4 megametres and then decline, the understanding of magic as malign (i.e., witchcraft/sorcery) altered in often dramatic ways, beginning with anxieties typical of agrarian communities, and culminating in Late Antiquity in charges of lese-majesty at court and routinized attempts at revenge by rival rhetors, to which we can add the deployment of allegations of magic by Christian hardliners in attacking paganism and heretics. A significant process in this history was the gradual appropriation over the last hundred and fifty years of the Republic of a term (magia) and its associated stereotypes from the Hellenistic Greek world, which together provided a medium, widely exploited in a variety of literary genres, for re-figuring the social disruptions that attended the violent self-destruction of the aristocratic régime and remained thereafter a powerful imaginative resource for constructing a variety of boundaries around a moral centre, claimed to be steady but in fact altering very considerably under shifting political, social, and religious conditions.