In this work, taken together with O'Donoghue's third edition (with new material) of F. E. Warren's The liturgy and ritual of the Celtic Church (Gorgias Press, 2010), O'Donoghue has rendered an immense service to students of early Irish church history and its liturgy. A second edition of Warren's work (first published in 1881) was published in 1987 with a new introduction by Jane Stevenson. In the third facsimile edition O'Donoghue presents a new introduction, setting Warren's original edition in its historical setting and giving a most informative update on the questions relating to the issues involved. Together with this, O'Donoghue provides a facsimile edition of two other very important, and now quite inaccessible, studies: the Revd B. McCarthy's ‘On the Stowe Missal’ (1886), which includes the Irish text of the Treatise on the Mass, Stowe and Leabhar Breac texts, with English translations, and Whitley Stokes's essay, ‘The Lebar Brecc tractate on the consecration of a Church’, originally published in 1901 in the Festschrift for G. Ascoli. The basis of the book under review was a thesis presented to St Patrick's College, Maynooth. There are three chapters, ‘Historical background’, ‘Written sources’, and ‘Archaeological and iconographic sources’, with a brief conclusion and an appendix comprising the Old Irish Tract on the Mass (in the Stowe and Leabhar Breac texts; the texts and translations are those of B. McCarthy). There are ninety-nine pages of endnotes, an excellent bibliography (twenty-eight pages) and a good index (six pages) of subjects and chief proper and place names. The first chapter – sixty pages with 355 endnotes – gives the relevant bibliographic reference to all the statements made by the author, some of the notes being quite extensive. This chapter covers in some detail all the relevant background questions on the Irish Church from its foundation to the Norman conquest: early relations and polemics between the Irish and English Churches, the Irish Church from the sixth the eighth century (organisation, scholarship and pastoral care), and similarly for the eleventh century until the coming of the Normans (renewal movements, church reform). There is a special section on the eucharist in the west until the twelfth century; development of the Gallican Rite and its probable use in Ireland. The existence of a specific Celtic rite is denied. Views on possible links with the east are discussed and evaluated. I notice the absence of Piotr O. Scholz's essay ‘Christlicher Orient and Irland’ (Nubia et Oriens Christianus, I: Festschrift C. Detletf G. Müller, 1987), from his bibliography and index. In this regard the evidence of the presence of papyrus in the cover of the recently discovered Faddan More Psalter (from about ad 800) now enters the equation. At the end of chapter one O'Donoghue notes that at the end of the eighth century the practice of eucharistic doves developed, suspended above the altar. This presented an excellent opportunity to note its presence in the Stowe Tract on the Mass: ‘super altare .i. turtur’ (thus ed. Stokes and Strachan), the manuscript reading turtur unfortunately misread by B. McCarthy as intrat (‘it enters’). This is an excellent work, and sure to become a classic in the field in the study of Irish liturgy and as a background to such works as the Stowe Tract on the Mass.