The purpose of this work is to list all the fifteenth-century books in the Cambridge University Library, to direct the reader to the best published descriptions of each book, to supplement published descriptions when they appear inadequate or inaccurate, and to describe the peculiarities and the provenance of the Cambridge copy.

The entries are arranged in Proctor's order and are numbered serially. Books which have been acquired since this numbering was completed have been inserted in the sequence by means of decimals. Whenever Proctor's attribution is no longer accepted, a cross-reference is given from the Proctor number to the number of the entry in the Catalogue where the book will now be found.

The first element in each entry is a statement of author, title, format, height of page, and date of publication when it appears in the book. Anonymous works are entered under the first word of the title, unless the title mentions a particular person, body of persons or place; and the same principle has been applied in the index of authors and anonymous titles. If a book contains ancillary pieces, additional to the main title, their presence is indicated by ‘[etc.]’ added after the title; and all such pieces are listed in the index of authors and anonymous titles, where their imprints are printed in italics.