Concurrent with the closing of the third session of Vatican Council II, on November 21, 1964, Pope Paul VI proclaimed that Mary was in fact Mother of the Church and promulgated the Council’s Dogmatic Constitution on the Church, Lumen Gentium. Lumen Gentium presents the doctrine on the Church in a new “light”, with the hope of “shining a light” on the inherent dignity of all people. The last chapter of Lumen Gentium, Chapter 8, is entitled: The Blessed Virgin Mary, Mother of God in the Mystery of Christ and the Church. A pivotal document, Lumen Gentium, marks the first time that an ecumenical council has dedicated an entire chapter of a dogmatic constitution to the Blessed Virgin Mary and her unique role with respect to Christ and the Church.
With joy, the Holy Father indicates that he is using this momentous occasion to fulfill a “wish”, held both personally and by many of the council Fathers, to proclaim the Blessed Virgin Mary, Mother of the Church. The Holy Father makes the proclamation as follows: “Therefore, for the glory of the Virgin Mary and for our own consolation, we proclaim the Most Blessed Mary Mother of the Church.” So it was on November 21, 1964 that the Blessed Virgin Mary, “officially” became “Mother of the Church”. While the Church has known this implicitly through Sacred Scripture, and the Early Church Fathers and more explicitly through the Ordinary Magisterium, it has never before been “officially” proclaimed until Pope Paul VI did so at the closing of Session 3 of the Vatican Council II.
The latest development is the announcement of February 11, 2018, by Pope Francis decreeing a new Memorial Feast in honor of Mary, Mother of the Church, to be celebrated annually on the Monday following Pentecost.