Index, in the Roman Catholic Church, list of publications forbidden to be read, called Index librorum prohibitorum [list of forbidden books]. This censorship was exercised by the Holy See. Catholics are forbidden, as a natural part of ethics, to read anything they know may endanger their faith or moral life; the Index was a partial guide to such literature. Since it was made up only from decisions referred for judgment on specific works, there was no consistency of inclusion; the failure of a book to appear in it implied nothing. The last edition of the Index was published in 1948. In 1966 the Congregation for the Doctrine of the Faith (formerly, the Holy Office) announced that the Index and its related penalties of excommunication would no longer have the force of law in the church.