Index Librorum Prohibitorum System

Timeline

1. 1526–1558Louvain and Venice · BelgiumAfter the outbreak of the Reformation, local lists of prohibited books were drawn up successively in Germany, the Low Countries, and Italy; attempts at unified censorship were also made at the papal and imperial levels, accumulating practical experience for the papacy's centralized compilation of an authoritative Index.
2. 1559Rome · LazioPope Paul IV promulgated the Index of Prohibited Books, banning a large number of books under unprecedentedly strict standards, provoking strong backlash from European scholars and prompting the papacy to revise and institutionalize censorship procedures after the Council of Trent.
3. 1563–1571Rome · LazioIn 1564 the Council of Trent approved a revised Index; Pope Pius IV established the Congregatio Indicis with sole responsibility for censorship and revision, and established the canon law requirement that diocesan permission be obtained before publication, formally making the Index system a permanent papal institution.
4. 1571–1966The Catholic world · AmericasThe Index system applied as Catholicism expanded worldwide, with successive revisions incorporating scientific, philosophical, and literary works. In 1966 Pope Paul VI abolished the Index, replacing mandatory prohibition with pastoral guidance from the Congregation for the Doctrine of the Faith, though its historical impact remains profound.