The dissertation is a study of the fascinating and variable approaches to translation and adaptation during the Middle Ages. I analyze four anonymous Middle English texts and two tales from Sir Thomas Malory's Le Morte Darthur that are translations and adaptations of Old French Arthurian romances. Through the comparison of the French and English romances, I demonstrate how English translators employed a variety of techniques including what we might define as close translation and loose adaptation. Malory, in particular, epitomizes the medieval translator. The two tales that receive attention in this project illustrate his use of translation and adaptation. Furthermore, the study is breaking new ground in the field of medieval studies since the work draws on translation theory in conjunction with textual analysis. Translation theory has forged a re-evaluation of translation as a literary medium. Using this growing field of research and scholarship, we can enhance our understanding of translation as it existed during the Middle Ages. For the medieval writer, translation was a fluid concept, and modern theoretical approaches are also highlighting the variety of approaches to translation. Thus, this project reveals that medieval translation is not only a distinct and important literary genre, but also provides new ways to think about translation and adaptation.