The Second Vatican Council which was forecast by Pope John XXIII January 25, 1959, was held in four sessions in St. Peter's Basilica in Vatican City. Pope John opened the first session, which ran from October 11 to December 8, 1962. After Pope John's death, Pope Paul VI reconvened the council for the other three sessions which ran from September 29 to December 4, 1963; September 14 to November 21, 1964; September 14 to December 8, 1965.
A total of 2,860 bishops and cardinals participated in council proceedings, and attendance at meetings varied between 2,000 to 2,500. For various reasons, including the denial of exit from Communist-dominated countries, 274 bishops could not attend.
The main business of the council was to explore and make explicit dimension of doctrine and Christian life requiring emphasis for the full development of the Church and the better accomplishment of its mission in the contemporary world. The Council formulated and promulgated sixteen documents, all of which reflect its basic pastoral orientation toward renewal and reform in the Church. (source: 2005 Catholic Almanac published by Our Sunday Visitor)