The volume constitutes the third publication of results of the project promoted by the Region of Tuscany in collaboration with SISMEL. It includes descriptions of 96 manuscripts dating to the XVth century and held in: Grosseto in the Biblioteca Comunale Chelliana and the Museo d'arte sacra della Diocesi; Massa Marittima in the Biblioteca Comunale "Gaetano Badii", the Cathedral of San Cerbone and the Church of Sant'Agostino; Montemerano in the Church of San Giorgio; Pitigliano in the Museo diocesano d'arte sacra; Prata in the Parish of Santa Maria Assunta; Livorno in the Archivio diocesano, the Biblioteca dei Cappuccini and the Biblioteca Comunale Labronica "Francesco Domenico Guerrazzi"; Castiglione del Terziere (Province of Massa) in the Biblioteca del Castello; Fivizzano (Province of Massa) in the Biblioteca Civica "Emanuele Gerini" and the Church of Santi Iacopo e Antonio. The publication is furnished with 113 plates, indices, a general bibliography, plus the history of the libraries and of their collections.