De vulgari eloquentia, written by Dante in the early years of the fourteenth century, is the only known work of medieval literary theory to have been produced by a practicing poet, and the first to assert the intrinsic superiority of living, vernacular languages over Latin. Steven Botterill here offers the only Latin-English parallel-text edition of an important early work by the author of the Divine Comedy, and the only English translation with thorough and up-to-date notes and introductory material.