Current historical positions on the origins and history of Christian martyrology generally take one of two positions. W. H. C. Frend, in his classic Martyrdom and Persecution in the Early Church, argues essentially that Christian martyrology is a "prolongation and supersession" of Jewish martyrology. In diametrical opposition, G. Bowersock, in his recent Martyrdom and Rome, argues that Christian martyrdom has nothing to do with Judaism or with the Palestinian cultural context of early Christianity, but is entirely a Roman cultural product, adapted for Christianity, and later borrowed from Christians by Jews. Both are dependent on the assumption of a clear and virtually absolute separate identity for the two religions in Late Antiquity. In the current essay, I shall try to show that we need to think of much more complex ways that Christianity and Judaism interacted during the crucial second, third, and fourth centuries, as well as of a much more nuanced understanding of the nature of martyrology itself. Martyrology is an overdetermined, multisourced discourse that undergoes significant development within late antique Judaism and Christianity. Many of the new elements can be shown to be shared by both religious groups, and the direction of "influence" is not only one-way. A model of close contact and dialogue between the two emerging "religions" seems to explain best the historical developments. The present essay is one part of the first of a series of planned monographs on such contact and dialogue with respect to the religious creativity of Judaism and Christianity in Late Antiquity.