As J. Koch has shown, the Commentary of the Sentences of Durandus of Durandus of St. Pourçain (1275-1334) is conserved in three versions. While the last redaction has been published in the 16th century, the first two have remained unpublished until now. The first redaction is of special interest, as it contains the most direct critique on Thomas Aquinas. It also inspired very critical reactions from Durand's contemporaries (such as Petrus de Palude and Petrus Aureoli). During the course of this project, a digitized version of the third redaction (ed. Venetiis 1571) is established, which will then be used as an efficient instrument of research. Nevertheless, the centerpiece of this project is the critical edition of the first version. This will be established on the basis of a complete collation of the manuscripts.