The treatise "On Dialects" by Gregory Pardos, a twelfth-century archbishop of Corinth, is one of the most important witnesses to the study of the ancient Greek dialects in antiquity and the Middle Ages. The project aims to produce an edition of the text: the first edition since 1811, and the first altogether to be based on all the surviving manuscripts and to be informed by modern text-critical standards. The edition will be prefaced by an analysis of the relationship between the manuscripts; a study of Gregory's sources, his methods as a linguist and as a compiler of earlier linguistic scholarship, and his place in the intellectual context of twelfth-century Byzantium; and an exploration of the transmission and reception of the treatise through an investigation of the manuscripts which preserve it. The data on which the edition will be based – the readings of the manuscripts – will be made freely available in full in the form of an online multi-text edition accounting for the diversity of forms which the treatise takes in the various manuscripts. The project sits at the intersection of several fields: Classics, Byzantine studies, manuscript studies, editorial theory, digital humanities. Methodological advances in these disparate fields will come together in the service of this worthwhile, long-awaited aim. Once published, the edition will establish itself as the state-of-the-art; it will enable further research to be conducted on (among others) ancient dialectology, twelfth-century Byzantine intellectual networks, Classical reception, and debates about the Greek language; and it will serve as proof of concept for a large-scale online multi-text edition. The research will be supervised by Prof. Alexander Riehle, a scholar of Byzantine intellectual culture and editor of Byzantine texts, in Harvard, and Prof. Olga Tribulato, an expert in ancient Greek linguistics and the study of the Greek language in antiquity, in Venice.