The origin of the Pontifical Council for Promoting Christian Unity is closely linked with the Second Vatican Council. It was Pope John XXIII's desire that the involvement of the Catholic Church in the contemporary ecumenical movement be one of the Council's chief concerns. Thus, on 5 June 1960, he established a "Secretariat for Promoting Christian Unity" as one of the preparatory commissions for the Council, and appointed Cardinal Augustin Bea as its first President. This was the first time that the Holy See had set up an office to deal uniquely with ecumenical affairs.

At first, the main function of the Secretariat was to invite the other Churches and World Communions to send observers to the Second Vatican Council. Already, however, from the first session (1962), by a decision of Pope John XXIII, it was placed on the same level as the conciliar commissions. The Secretariat thus prepared and presented to the Council the documents on ecumenism (Unitatis redintegratio), on non-Christian religions (Nostra aetate), on religious liberty (Dignitatis humanae) and, together with the doctrinal commission, the dogmatic Constitution on Divine Revelation (Dei Verbum).

In 1963, the Holy Father specified that the Secretariat would be made up of two sections dealing respectively with the Orthodox Churches and ancient Oriental Churches on the one hand and with the Western Churches and Ecclesial Communities on the other.

In 1966, after the Council had ended, Pope Paul VI confirmed the Secretariat for Promoting Christian Unity as a permanent dicastery of the Holy See. Cardinal Bea continued in office as President until his death in 1968. In 1969, Cardinal Johannes Willebrands was named President to succeed him. Twenty years later, he retired and became President Emeritus. Cardinal Edward Idris Cassidy was then named President of this Pontifical Council.

In the Apostolic Constitution Pastor Bonus (28 June 1988), Pope John Paul II changed the Secretariat into the Pontifical Council for Promoting Christian Unity (PCPCU); this new designation took effect as of 1st March 1989.

The Council exercises a double role. First of all, it is entrusted with the promotion, within the Catholic Church, of an authentic ecumenical spirit according to the conciliar decree Unitatis redintegratio; it was for this purpose that an Ecumenical Directory was published in 1967-1970 and a revised edition issued in 1993 entitled "Directory for the Application of Principles and Norms on Ecumenism". The Council carries out this task in liaison with the various departments of the Roman Curia, whose competence includes areas that can contribute similarly to the task of dialogue of the Catholic Church and should be put to the service of its relationships with all the Churches and ecclesial Communities.

At the same time, the Pontifical Council also aims to develop dialogue and collaboration with the other Churches and World Communions. Since its creation, it has also established a cordial cooperation with the World Council of Churches (WCC), whose headquarters are in Geneva. From 1968, twelve Catholic theologians have been members of the "Faith and Order" Commission, the theological department of the WCC.

Similarly, it is the task of the PCPCU to name Catholic observers at various ecumenical gatherings and in its turn to invite observers or "fraternal delegates" of other Churches or ecclesial Communities to major events of the Catholic Church.

At present, the PCPCU is engaged in an international theological dialogue with each of the following Churches and World Communions:

• The Orthodox Church
• The Coptic Orthodox Church
• The Malankara Churches
• The Anglican Communion
• The Lutheran World Federation
• The World Alliance of Reformed Churches
• The World Methodist Council
• The Baptist World Alliance
• The Christian Church (Disciples of Christ)
• Some Pentecostal groups.

The Council also seeks to promote meetings with Evangelicals.

In order to make known as widely as possible the results of its work towards Christian Unity, the PCPCU publishes a journal called Information Service four times a year, in English and French.

The Pontifical Council is under the direction of the Cardinal President. He is assisted by a Secretary, a Joint Secretary and an Under-Secretary. The relations with other Churches and ecclesial Communities are divided into two sections:

• The Eastern section deals with Orthodox Churches of Byzantine tradition and the Oriental Orthodox Churches (Coptic, Syrian, Armenian, Ethiopian and Malankara), as well as the Assyrian Church of the East;
• the Western section is responsible for the different Churches and ecclesial Communities of the West and for the World Council of Churches.

Collaboration for the Diffusion of the Bible

Following the responsibility undertaken by the then Secretariat for the preparation of the dogmatic Constitution on Divine Revelation, the PCPCU was entrusted with promoting ecumenical collaboration for the translation and diffusion of Holy Scripture (Dei Verbum, n. 22). In this context, it encouraged the formation of the Catholic Biblical Federation, with which it is in close contact. Together with the United Bible Societies it published the Guidelines for Interconfessional Cooperation in Translating the Bible (1968; new revised edition 1987).

The Catholic Committee for Cultural Collaboration

Founded in 1963, the Committee seeks to promote, between the Catholic Church and the Orthodox Churches of the Byzantine tradition and the Oriental Orthodox Churches, exchanges of students, who wish to follow theological studies or other ecclesiastical disciplines at Catholic or Orthodox institutions. An international Committee for the awarding of scholarships, which depends on the Committee, meets every year in March.

Relations with the Jews

On 22nd October 1974, Pope Paul VI established a Commission for Religious Relations with the Jews as an office distinct from but closely linked with the PCPCU. In fact, the Cardinal President of the PCPCU presides over this Commission; the Secretary of the PCPCU is similarly its Vice-President. A full-time executive Secretary ensures the day-to-day running of the Commission. In order to implement the guidelines of the Second Vatican Council, the Commission published Guidelines and Suggestions for Implementing the Conciliar Declaration "Nostra aetate" n. 4, (1974) and Notes on the Correct Way to Present the Jews and Judaism in Preaching and Catechesis in the Roman Catholic Church (1985).