Conversations with the Calabrian abbot Joachim of Fiore (c. 1135-1202) had a way of turning to the imminent advent of Antichrist: "Antichrist was coming very soon," Joachim might say, or "Antichrist was already born in Rome," or "the age culminating in Antichrist's persecutions will begin in a mere four years."1 It is hence not surprising that Joachim became most famous in his own lifetime as a prophet of Antichrist. But how exactly did Joachim's warnings concerning Antichrist's imminent advent fit in with his overall view of the history of salvation? Joachim's contemporaries had more difficulty in understanding this larger issue than they had in grasping his urgent message that Antichrist was coming soon, and central questions concerning the nature of Joachim's Antichrist thought still have not been resolved by modern scholarship. Above all, two problems of interpretation remain outstanding: (1) Given the certainty that Joachim actually believed in the coming of many Antichrists, which of these several was for him the "real and true" one? (2) Given that Joachirn's "real and true" Antichrist can indeed be identified, how did his conception of this eschatological villain compare with that of prior medieval tradition? In seeking to answer both questions I hope to show concurrently that Joachim's Antichrist theology was enormously innovative, daring, and subtle, as his thinking was in so many other regards.