The Council of Trent (1545–1563) initiated a period of liturgical standardization in the Roman Catholic church. Catholic worship remained largely uniform throughout the world until the appearance of the Constitution on the Sacred Liturgy of the Second Vatican Council (1963).
Pius IV confirmed the decrees of the council in 1564 and they set the standard of faith for the Catholic Church until the mid-20th century.
The change in the worship experience of twentieth-century Roman Catholics may be appreciated by briefly looking at history. In the sixteenth century, Reformers had posed challenges to the lack of intelligibility of medieval Catholic worship experience to the laity. The Council of Trent (1545-1563) responded to the challenge by revising liturgical books, but the Latin language was retained and the textual uniformity remained.