The paper presents the ongoing project of editing and publishing medieval Waldensian sermons, which is a corpus of nearly 200 texts written an eastern variety of medieval Occitan. The texts are preserved in manuscripts dating to the late fifteenth through early sixteenth centuries. The first part of this paper provides information about the corpus and its history, including a brief summary of academic work on these texts since the end of the nineteenth century. The second part deals with some important aspects of the current project. Besides editing and publishing the texts, the project aims to investigate in detail other questions posed by the manuscripts (such as their genesis, manufacture, palaeographic and codicological features, and so on) and to identify the sources used in the sermons. In this regard, Iacobus de Varagine’s Sermones deserves particular attention.