The feast of the Crown of Thorns was one of the most important and enduring among the numerous cults that arose in medieval times, focusing on the supposed relics of Christ's Passion. As such, the feast provided the stimulus for the wide dissemination of a succession of liturgies, often with sections in picturesque devotional language. Very few sources of these liturgies survive complete with music. One of them, Liverpool University Library manuscript F.4.13, a 14th-century antiphoner from Pisa, is the principal subject of the present article. The Liverpool manuscript contains what we believe to be the only extant complete text with music of this version of both Office and Mass. As will become clear, the version is neither of the two commonest extant offices, which are Parisian and Dominican respectively; instead, it appears to reproduce an earlier and fuller form of the Dominican office than can be found in other Dominican books. We examine the texts and music of the Liverpool manuscript, together with associated evidence, and provide a discussion of the history of the feast and its special promotion by the Dominican order.