The Use of Hereford, a local variation of the Roman rite, was one of the diocesan liturgies of medieval England before their abolition and replacement by the Book of Common Prayer in 1549. Unlike the widespread Use of Sarum, the Use of Hereford was confined principally to its diocese, which helped to maintain its individuality until the Reformation. This study seeks to catalogue and evaluate all the known surviving sources of the Use of Hereford, with particular reference to the missals and gradual, which so far have received little attention. In addition to these a variety of other material has been examined, including a number of little-known or unknown important fragments of early Hereford service-books dismembered at the Reformation and now hidden away as binding or other scrap in libraries and record offices. This is the fullest examination of Hereford liturgical sources ever undertaken and may stimulate similar and much-needed studies of other diocesan uses, in particular Sarum and York. As well as describing in detail the various manuscript sources, the rare single edition printed Hereford texts, the missals and breviaries, are also discussed. Unlike books of the Sarum and York rites, these 'one-offs' were never revised and reissued. In addition to the examination of these sources, William Smith discusses the possible origins of the rite and provides an analysis of the Hereford liturgical calendar, of the festa, including those of the cathedral's patron St Ethelbert and the no less famous St Thomas Cantilupe, that helped to make Hereford use so distinctive.