This article examines the development of the idea of “Late Antiquity” from its origins in the early twentieth century among art historians, to the launch of the “Late Antiquity Project” with the publication of Peter Brown’s The World of Late Antiquity in 1971. The preface to this book, and a postscript to the new edition of 1993, are analyzed in terms of the ideologies which they reveal. There is discussion of the achievements of scholars of Late Antiquity over the last thirty-five years, above all in correcting the geographical bias of earlier work and in bringing in many new aspects of Late Roman society into historical light. But the study ends by expressing a number of worries about the new late antique orthodoxy—about the emphasis on “continuity” and “transformation”, in particular—that threaten to be as distorting of the ancient world as the old orthodoxy was.