The view that early Christians neither defined themselves nor were perceived in terms of race or ethnicity finds support in a broad spectrum of scholarly and popular thought.This article is revised from a lecture delivered in the New Testament and Early Christian Studies Lecture Series at the Harvard Divinity School on November 7, 2000. A fellowship in the Bunting Fellowship Program at the Radcliffe Institute for Advanced Study this year has enabled me to write the book to which this article pertains. Caroline Johnson Hodge, Cathy Silber, Francesca Sawaya, Augusta Rohrbach, Lisa Herschbach, and especially Karen King offered valuable suggestions in the preparation of the piece. In addition, Bernadette Brooten, François Bovon, Ellen Aitken, Larry Wills, Yuko Taniguchi, and Adam Marlowe provided useful feedback on the lecture. I want to suggest, however, that ethnicity and race have in fact been central to formulations of early Christian self-definition—in two quite different ways, one historical and the other historiographic. First, ancient ideas about race and ethnicity were valuable for early Christians in their varying attempts to define Christianness; many early Christians defined themselves using ethnic reasoning, that is, by using language that their contemporaries would have understood as racial or ethnic. Second, modern ideas about race and ethnicity, as well as about religion, have also shaped understandings of early Christian self-definition but have led to the opposite conclusion—namely, that Christians, from the very beginning, viewed race as a form of human difference to be transcended or made irrelevant.