The theatre library owns about 40.000 volumes, coming from gifts and purchases. The book collections range from XVIth century editions to contemporary publications. They include theatre works of all ages, nations, genres, critical essays and histories of theatre and performing arts in all their forms, reference books and repertories, library science professional literature.
Particularly important are the XVIth and XVIIth century editions (respectively 244 and 346 volumes). Among the first, stand out the Latin translation of Sophocles' tragedies published in Venice in 1543 by Giovanni da Borgofranco, Aristophanes' plays in Greek original text (Florence, Bernardo Giunta 1515 and Benedetto Giunta 1540) and in Italian version (Venice, 1545), Plautus'comedies in Latin printed by Lazzaro Soardi in Venice in 1511 (the oldest book belonging to the library collections), Terence's plays in Latin (1553 and 1569), Seneca's works translated by Lodovico Dolce (1560). The Italian theatre of the XVIth century is present in coeval editions: comedies by Ariosto, Ruzante, Machiavelli, Aretino, Calmo, Dolce, Cecchi, Lasca. Several are the descriptions of feasts and tournaments.
Worthy to be remembered are also the treatises on different subjects: Delle antichità di Roma nel quale si tratta de' circi, theatri et anfitheatri... by Pirro Ligorio (1553), La pratica della perspettiva... by Daniele Barbaro (1568), Della poesia rappresentativa e del modo di rappresentare le favole sceniche by Angelo Ingegneri (1598).
From the XVIIth century increases remarkably the presence of the Commedia dell'Arte, with the comedians families, such as the Andreini (Isabella, Francesco and Giovan Battista), with many editions of their letters, rhymes and plays, and the big number of treatises for and against theatre (Della christiana moderatione del theatro by G. Domenico Ottonelli, 1615; Brevi discorsi intorno alle commedie, commedianti et spettatori by Pier Maria Cecchini, 1621; La Supplica by Niccolò Barbieri, 1634; Dell'arte rappresentativa premeditata e all'improvviso by Andrea Perrucci, 1699).
Particularly valuable are the large volumes of plates, such as Le costume historique by Albert Racinet and Denkmäler des Theaters by Joseph Gregor, and the five-volume edition of the sketches by Carlo Ferrario, scenographer at La Scala theatre (1913).