For practical reasons, this paper concerns not the complete corpus of Norman liturgical books, but simply those which contain music for mass (or information about it). The sources upon which my survey is based are listed in Table 1 on pages 14–16. They are grouped according to place of origin, in four sets: sources from (i) Normandy, (ii) areas of north France adjacent to Normandy, (iii) Britain, (iv) Sicily, South Italy and the Holy Land. When more than one source survives from a particular church, each is distinguished by a readily comprehensible qualifier in square brackets. The contents of the chosen sources are examined from six main points of view: post-Pentecost alleluia series, then the complete alleluia, sequence and ordinary of mass repertories, and finally variant readings in proper of mass chants and in sequences. The crosses in the columns opposite each source in Table 1 indicate that the source has been used in one of the six types of investigation. Thus the troper from St Evroult (Paris, Bibl. Nat., lat. 10508) contains material for a study of alleluia, sequence and ordinary of mass repertories, and the text and melody variants in sequences; but for the St Evroult post-Pentecost alleluia series one must consult the sacramentary Rouen, Bibl. Mun., 273, which has chant text incipits in its margin. No St Evroult book survives with chant melodies for all the proper of mass, so St Evroult must remain unrepresented in the study of melodic variants in the proper of mass. It goes without saying that some books can be assigned more confidently than others to particular churches. Table 1 is therefore followed by brief notes explaining the more tentative or less widely known among the assignations I have made. The churches of Normandy mentioned in this paper are shown in Map 1 on page 18.