The Catalan Dominican Ramon Martí (d. after 1284) was the most learned polemical author of the later Middle Ages. He was part of the thirteenth-century Dominican interest in missionizing and language learning in Aragon under the auspices of Ramon of Penyafort, interest that led to the famous Disputation of Barcelona in 1263 between Friar Paul Christiani and the great Rabbi of Girona, Moses ben Nahman (Nahmanides).Following in the wake of this debate, Martí developed many of its key arguments and strategies. In order to do so, Martí learned Arabic, Hebrew, and Aramaic and probably taught one or all of these languages to fellow Dominicans as well. His writing (two polemical works against Islam and two more against Judaism, including the massive Pugio fidei, or "Dagger of Faith" from 1278) makes ample use of original source material in these three Semitic languages, and cites and translates widely from Jewish and Muslim religious and philosophical sources. Despite the increasing attention that Martí's work has received in recent years, scholars have only scratched the surface of his abundant and complex corpus of writings, and much work (both editorial and interpretive) remains to be done in assessing Martí's important role in Christian relations with Jews and Muslims in Iberia as well as in Christian intellectual history more generally. These two talks will consider a few dimensions of Martí's work in detail, demonstrating Martí's profound importance for scholars of the Middle Ages in general, but especially for those interested in language learning in the later Middle Ages and Christian engagement with other faiths in this period.