THE CHARTERS OF THE ABBEY OF Y STRAD Marchell. Edited by Graham C. G. Thomas. The National Library of Wales, Aberystwyth, 1997. Pp. xi, 239; 9 plates; 3 maps. £ 25.00. This beautifully produced volume presenting the surviving charters of Ystrad Marchell must be warmly welcomed. It presents full texts of fifty- eight charters, a calendar of eleven late medieval charters and the summaries of thirty-two entries in a royal inspeximus of 1322/23. The texts are arranged in date order. Forty-nine originals survive, the largest group for any Welsh abbey, with the sole exception of Margam. One of these concerns Valle Crucis abbey and is given in an appendix because it was included by J. Conway Davies in his calendar of material from Ystrad Marchell. Hitherto, although most of the texts were known about, they were only available in inadequate versions, or in Davies's calendar, whose transcripts of personal and place-names are here described as 'riddled with errors'. Such words perhaps are hostages to fortune, and this reviewer is certainly not equipped with the linguistic and topographical skills necessary to check those aspects of Dr Thomas's work. Other aspects of his transcriptions give one confidence, although the phrase 'Et quia moderna generatis in number 22 might read 'moderna generatio'. The edition covers 93 pages and is preceded by an introduction of 141: this is a generous relationship, allowing for very interesting discussions about many problems, but which in many editions would have been subsumed into notes at the end of each text. Here each text is only accompanied by its location, physical description, list of endorsements, references to previous editions or calendars, and finally cross-references to pages in the introduction. Each charter is preceded by a very full summary in English, one feature of which is rather strange. Personal and place- names are usually given there in the form that they occur in each charter, and not standardized to the version preferred in the lists of names and places in the introduction. This has some puzzling results. In two successive documents (nos. 68, 69), Gruffudd ap (Prince) Llywelyn of north Wales of the introduction, who appears in the texts as 'Grifinus filius Lewelini principis' and 'Griffmus films Liwelini principis', turns into 'Griffudd son of Lewelin, prince' and 'Griffudd son of Liwelin, prince' in the summaries. I really can not understand what is happening here. The introduction is full of good things: particularly interesting is the analysis of the charters written before 1215 which gives good reasons for believing that most of them were written at the abbey itself. Altogether twenty-five hands are identified, and illustrated with very clear photographs. It is a pity, though, that references to these are not given among the material