Guillaume de Machaut, a pioneer of a new school of lyric compositions, is the most important poet and composer of late medieval France. This long overdue new edition of Machaut's twenty-three motets, the largest surviving collection of such works by a single composer in this period, is based on the most authoritative of the surviving manuscripts and is designed to meet the needs both of advanced scholars and musicians as well as students and performers. This user-friendly format indicates variants on the scores and has a layout that makes each work's structure clearly visible; the lyrics, with full English translation, are presented at the end of each work. The supporting materials include: an introduction that discusses the life of the author and his artistic achievement and provides fresh insights into the poetry and music of the motets; notes for their performance and pronunciation; an art-historical commentary on the accompanying manuscript illuminations; and detailed commentaries, including collation of manuscript variants, for each motet.