I have been able to include in the catalogue of Indexes certain titles which were not listed by Reusch, and I have added the record of the Indexes which have been published since the date of Reusch’s treatise. I have not been dependent upon Reusch’s schedules for the contents of the Indexes themselves, as I have been able to make a personal examination of all of the more important Indexes in the series from examples in my own library, and in the comprehensive collection of my valued friend Mr. Archer M. Huntington. Mr. Huntington has, I may mention, rendered a most important service to students of the Index through his reprints, produced in facsimile, of five of the earlier issues as follows: Louvain, 1546; Louvain, 1550; Cordova, 1550; Cordova, 1554; Valladolid, 1559. Certain Indexes have been selected from the long series as on one ground or another entitled to special attention. For these I have given, in addition to some analysis of the prefatory matter, the accompanying Bull and the regulations, and a specification of the more important of the literature which is represented in the lists of the books condemned. Among the Indexes that call for such fuller description and analysis are the following: Louvain, 1546, (usually classed as the first in the series of the Church Indexes); Rome, 1559, (the first in the series of papal Indexes); Trent, 1564, (the papal Index which secured the widest and most continued influence); Rome, 1607, (the only expurgatory Index in the papal series); Rome, 1664, (in which is presented the condemnation of Galileo); Rome, 1758, (the Index which marked the beginning of the wider literary policy for the Church); Rome, 1900, (the latest of the papal Indexes and the one which must, therefore, be taken as expressing the present literary policy of Rome). I have also given, with some detail, analyses of certain of the Spanish expurgatory Indexes, as these present a class of censorship quite distinct in character and not attempted outside of Spain. Separate chapters are devoted to the treatment throughout the series of Indexes of certain subjects of continued importance, such as the relations between the Church and State, the consideration given to Erasmus and to Luther, the treatment of the monastic orders, etc. In Chapter IX of the second volume, is presented a study of the influence of the Index upon the book-trade in the several States of Europe. While there are in existence no trustworthy statistics for such a record, certain general results can be determined from the history of the printer-publishers and from the transfer of the centres of book production and distribution from the States which were under the direct control of the Index regulations to territories in which the action of censorship was less effective, or, as in Holland, non-existent.