In the 1930s, Oregon State University received an impressive oversized manuscript, now known as "The Gradual," as part of a large donation of books. Not much was known about this manuscript. It does not have documentation attached from the time of its acquisition, nor had any methodical study been undertaken regarding the manuscript. This thesis examines the OSU Gradual, aiming to provide research tools for the identification of musical manuscripts of unknown or unclear provenance that could be useful to conservators, archivists, and librarians, irrespective of musical training. It is conceived as a "rough guide" for working situations where there is no dedicated manuscript specialist, in particular, a fulltime Latin paleographer or a chant scholar overseeing a massive collection. Instead, its "how-to" nature addresses curators and catalogers managing smaller manuscript collections as generalists, offering an interdisciplinary approach both beneficial and suitable to the aims of this study.