This critical edition of Liber III of the Reuelaciones of Saint Birgitta of Sweden is based on the readings of selected, medieval manuscripts. Furthermore, the text of the Editio princeps (impr. B. Ghotan, Lübeck 1492) has been used. The edition also contains an apparatus criticus, an apparatus fontium, a bibliography, an introduction to the history of the manuscripts and the text, a glossary and indices of grammar, literary sources, names and places, together with an excursus on the use of the Old Swedish text(s) in Book III and another one on a Latin Message, an original draft, corresponding to Book III 8 and 9. Keywords: St. Birgitta, St. Bridget, Revelation, Spirituality.