The Isabella Stewart Gardner Museum in Boston houses over thirty Venetian manuscripts dating from the fifteenth to eighteenth centuries. They comprise official documents issued by the Doges; histories of the Republic of Venice, its government, and the patriciate; diplomas; and a statute book of a lay confraternity. Most volumes contain complete and dated texts, are illuminated, and survive in their original bindings. The collection, therefore, charts the evolution over three centuries of Venetian book production, and provides a wealth of sources for the study of Venetian history, portraiture, iconography, genealogy, and heraldry. Isabella Stewart Gardner (1840–1924) purchased many of her Venetian manuscripts en bloc in 1903 from the Harvard University professor Charles Eliot Norton (1827–1907). Norton placed his collection formed in Venice in Gardner’s newly-opened museum to safeguard it from dispersal and mutilation for its miniatures and bindings. Drawing on Gardner and Norton’s unpublished correspondence and acquisition documents in the archives of the Isabella Stewart Gardner Museum and Harvard University, this article reconstructs the formation of one of the most important collections of Venetian manuscripts outside of Venice and presents a hitherto unknown episode of the preservation of illuminated manuscripts by two prominent Gilded Age American collectors.