An established consensus included in almost every recent study of Orderic Vitalis's life and works suggests that he acted as librarian of Saint-Évroul. His well-documented role in helping to compile the twelfth-century Saint-Évroul book-list, and his identified activities in reviewing and correcting manuscripts completed by other, perhaps more junior, scribes, have encouraged several notable, if brief, statements on the topic. Chibnall argued that in adding to the book-list and the calendar of Saint-Évroul's ‘chapter-book’, Orderic was ‘perhaps acting as librarian’, and elsewhere suggested that he had worked as an armarius. Similarly, Nortier cited Orderic's role in the book-list in the course of her proposition that the list was compiled, and perhaps even ordered, by Orderic's authority. Van Houts suggested that Orderic's corrections to several manuscripts highlight his possible roles ‘in charge of the scriptorium at Saint-Évroul and perhaps librarian and archivist as well’. More recent are Escudier's remarks that Orderic worked as librarian for the last thirty years of his life.

Despite the frequency of this claim that Orderic was librarian at Saint-Évroul, the precise circumstances in which he was given charge of books within the community, and the exact duties associated with the role, remain surprisingly little explored given their potential significance within the study of Orderic's life and works. The discussion which follows attempts a detailed analysis of Orderic as librarian at Saint-Évroul, drawing on evidence from within the Historia ecclesiastica, alongside a fresh examination of his additions to the surviving corpus of Saint-Évroul manuscripts, in order to understand the nature of his role more accurately and comprehensively.

As Chibnall noted, a monastic librarian active in Normandy during the eleventh and twelfth centuries was likely to have been an appointed official known as an armarius. While descriptions of this role are found in a number of contemporary guides to the organisation of communal religious life, the position is also sometimes referred to as that of precentor, or the more common form of cantor. For example, a mid-eleventh-century Cluniac text known as the Liber tramitis uses both cantor and armarius, while Ulrich of Zell's near-contemporary Consuetudines antiquiares Cluniacenses uses precentor and armarius.