The volume constitutes the first attempt at a reconstruction of the lost register of Celestine V’s papal bulls. The 90 original bulls recovered through this survey were written according to the standards of the Papal Chancery and attest to the activity of 31 scriptores. The study discusses the issues concerning the retrieval of these texts, their typology, their chronology and their edition, and also contains a thematic summary of all the bulls published in the book.