This article examines the Roman tradition that Numa once negotiated with Jupiter about human sacrifice. Complete versions of the myth survive in Ovid, Plutarch and Arnobius. Previous studies of this tradition have proposed four main interpretations of it, which have done important service in modern reconstructions of the character of Roman religion. These scholarly treatments raise several questions. First, are they actually supported by, or the most convincing way of reading, the surviving ancient sources? If so, have they been correctly (...) attributed? Why might a specific ancient author present the myth of Numa and Jupiter in a manner which suggests one interpretation rather than another? What ideological and theological work does the story do for Ovid, for Plutarch and for Arnobius? Finally, can this myth, in whatever version, support the weight of the implications put on it for the character of Roman religion? This article seeks to enhance our understanding of this myth in its surviving versions, not just by analysing the evidence for each of the modern interpretations, but also by considering why ancient authors tell the myth of Numa and Jupiter the way they do. It is argued that their choices illustrate best not one meaning of the myth nor one Roman way of piety but the richness and diversity of religious reflection in antiquity. (shrink)