Sicardus of Cremona (c. 1150–1215) is regrettably an obscure but vitally important source for students of medieval liturgy. Educated at the University of Bologna, he taught canon law at the University of Paris before becoming bishop of Cremona. A prolific writer across a variety of disciplines, Sicardus was well-known in his own day for a three-part commentary on Gratian's Decretum and a universal chronicle or world history. His allegorical exposition of the Latin liturgy, the Mitrale, still ranks as one of the most significant contributions to this medieval genre. I became quite familiar with Sicardus in my work as co-editor of the modern critical edition of the Rationale divinorum officiorum of William Durandus of Mende (c. 1230–96). Before the publication of Durandus’ renowned exposition (c. 1294–6), the Mitrale was by far the most extensive single-volume commentary on the liturgy (the new edition of the text is over 800 pages in length). Divided into nine books, Sicardus’ work was the source of a substantial portion of Durandus’ own treatise, often incorporated verbatim throughout the first seven books of the Rationale. More than any other work, the Mitrale served as both the editorial and textual exemplar for Durandus’ full commentary. As I noted in the introductory material to the critical edition of the Rationale, Durandus rarely cited the authors that he employed, but Sicardus is frequently identified, making him Durandus’ most quoted liturgical expositor. The fact that Sicardus was primarily a canonist who turned his attention to liturgical exposition might have privileged him in the eyes of his imitator, Durandus, a fellow canonist and bishop. The Mitrale appeared at a pivotal moment in the history of Latin Christendom. The political and theological tumult of the Investiture Controversy gave way to the construction of the magnificent cathedrals and abbey churches that are synonymous with late medieval art and architecture. Protracted debates over the liturgical ceremony of investiture, the transition from cathedral schools to universities, and the massive construction projects that began to dot the landscape of Europe provided a fertile environment for twelfth-century liturgical expositors. Rupert of Deutz, Honorius Augustodunensis, Pseudo-Hugh of St Victor, the anonymous Liber Quare, the scholastic Summa of John Beleth, and the mass exposition of Lothario of Segni (the future Innocent iii), provided thirteenth-century commentators such as Durandus with a voluminous library of liturgical works that could be pillaged for the composition of his own encyclopedic treatise. That Sicardus’ Mitrale stood in such a crowded field of texts may account for its neglect among modern scholars of medieval liturgy. Published in a diplomatic edition in J. P. Migne's Patrologia Latina (1855), the Mitrale has never been the object of the serious study that produced modern editions of the liturgical expositions of many of the aforesaid authors, including Durandus (most of these have been published in the Continuatio Mediaevalis series of Corpus Christianorum). The new edition of Sicardus’ work is therefore a long overdue addition to the critical texts available for students of medieval liturgy. The editors have identified eleven manuscripts that have been collated against the editio princeps of the Patrologia Latina edition. Aside from an apparatus criticus, the new edition has a running apparatus fontium that includes biblical citations, patristic and medieval authors, medieval liturgical expositors and liturgical texts. This reference material is supplemented with excellent indices. Overall, the presentation is what we have come to expect from the Continuatio Mediaevalis series. If there is a deficit, it is in the introductory material. The fine points of manuscript transmission are exceptionally well covered, but the presentation on the life and work of Sicardus and his place in the long tradition of liturgical commentary is offered in only the simplest of terms. But the editors undoubtedly anticipated the publication of their German translation of the full work, in the new series, Corpus Christianorum in Translation, where considerably more of that material can be found (Sicard von Cremona: Mitralis der Gottesdienst der Kirche, Turnhout 2011). The introductory material in the new German translation also includes addenda and corrigenda for the Latin edition. The necessity of using the new translation in tandem with the Latin text should not detract from the high quality of the scholarship represented by this volume. It will be received with great enthusiasm by students of medieval liturgy, and, with this fine new edition of his commentary. Sicardus can now assume his rightful place among the great liturgical expositors of the Middle Ages.