Second Vatican Council: The third session of the Roman Catholic Church's ecumenical council closes.

The Second Ecumenical Council of the Vatican, commonly known as the Second Vatican Council or Vatican II, was the 21st and most recent ecumenical council of the Catholic Church. The council met each autumn from 1962 to 1965 in St. Peter's Basilica in Vatican City for sessions of 8 and 12 weeks.

The Catholic Church, also known as the Roman Catholic Church, is the largest Christian church, with 1.27 to 1.41 billion baptized Catholics worldwide as of 2025. It is among the world's oldest and largest international institutions and has played a prominent role in the history and development of Western civilization. The Church consists of 24 sui iuris (autonomous) churches, including the Latin Church and 23 Eastern Catholic Churches, which comprise almost 3,500 dioceses and eparchies around the world, each overseen by one or more bishops. The pope, who is the bishop of Rome, is the chief pastor of the church.

An ecumenical council, also called general council, is a meeting of bishops and other church authorities to consider and rule on questions of Christian doctrine, administration, discipline, and other matters in which those entitled to vote are convoked from the whole world (oikoumene) and which secures the approbation of the whole Church.