Scholars have typically characterized Warsaw, Biblioteka Narodowa, I. 3311, an unlocalized Anglo-Saxon gospel lectionary of the late tenth or early eleventh century, as a book intended for use in private devotional reading. Despite this, a study of the contents of the book indicates that it was used liturgically, possibly by an individual priest or a small clerical community. This article offers a reappraisal of the manuscript and its use based on the complementary pattern of gospel readings that is evident in the two sections of the book and the presence of previously unnoticed musical notation. It is argued that the volume was in fact used in the celebration of mass and should be added to the corpus of Anglo-Saxon liturgical books.