Anglican interest in ecumenical dialogue can be traced back to the time of the Reformation and dialogues with both Orthodox and Lutheran churches in the sixteenth century. In the nineteenth century, with the rise of the Oxford Movement, there arose greater concern for reunion of the churches of "Catholic confession". This desire to work towards full communion with other denominations led to the development of the Chicago–Lambeth Quadrilateral, approved by the Third Lambeth Conference of 1888. The four points (the sufficiency of scripture, as the "ultimate standard of faith", the historic creeds, the two dominical sacraments, and the historic episcopate) were stipulated as the basis for church unity, "a basis on which approach may be by God's blessing made towards Home Reunion".

Although they are not considered members, some non-Anglican bodies have entered into communion with the Anglican Communion as a whole or with its constituent member churches, such as the Old Catholic Church, the Lutheran Churches (including those within the Porvoo Communion, the Evangelical Lutheran Church in America, and the Evangelical Lutheran Church in Canada), as well as the Malankara Mar Thoma Syrian Church.

Diplomatic ecumenism: quest for Christian unity

World Council of Churches Ecumenical dialogue has been particularly fruitful in three realms. The first is the World Council of Churches and its predecessors, in which Anglicans have been involved from the first. Anglican representatives were particularly involved in the development of the seminal Faith and Order paper, Baptism, Eucharist, and Ministry, which sought to develop common ground concerning these issues, and have been at the centre of the process of developing recent work on the "Nature and Mission of the Church".

Roman Catholic Church

The second concerns dialogue with the Roman Catholic Church. Long-term hostility between the two Communions was engendered by resistance in England to the declaration of royal supremacy, the confiscation of Church properties, the dissolution of the monasteries, the execution of priests, forced attendance at Anglican worship, forced payment of tithes to the state church and the illegalization of the Catholic faith. There was a brief restoration of communion with Rome during the reign of Mary I. Her death marked the end of Catholic attempts to reconcile by law the English Church to Rome. Subsequently, Pope Pius V's excommunication of Elizabeth I in 1570 and authorization of rebellion against her contributed to official suspicion of the allegiances of English Catholics. This, combined with a desire to assert the claims of the established church, led initially to renewed persecution by the state, and to the continued enforcement of severe legal restrictions. Most of these restrictions endured for 250 years and were only relieved through several legislative reforms in the 19th century, cumulatively known as Catholic emancipation. The prohibition on Catholics succeeding to the British Crown (and by extension the other Commonwealth realms) remains in effect.

Lutheran and Old Catholic Churches

Another fruitful realm of dialogue has been with various Lutheran churches. An ecumenical report titled "On Closer Acquaintance" noted that Anglicans and Lutherans are "the closest ecumenical cousins in Christendom." On the doctrine of justification, the Anglican Consultative Council (ACC) "recognises that Anglicans and Lutherans share a common understanding of God’s justifying grace...that we are accounted righteous and are made righteous before God only by grace through faith because of the merits of our Lord and Saviour Jesus Christ, and not on account of our works or merits."

Historically, the Church of England and the state churches of current (and former) mainland European monarchies where Lutheran Protestantism was the official doctrine, have had amicable relations. This has, in part, been nurtured by marriages between members of the Royal Family of Great Britain and the royal (Protestant) houses of Europe, especially the descendants of Queen Victoria (whose husband, Prince Albert, was a Lutheran).Weintraub, S., Uncrowned King: The Life of Prince Albert, p41, "Ernest recalled his pleasure that 'no formula' or 'strict confesion of faith' was forced on them: they responded to their examiner, insread, 'with a surprising amount of familiarity with church question'. As for the 'natural piety' ascribed later to Albert, his brother noted wryly, 'it was probably on the account of the English public, for this description suited him certain even less than it me'. The rite required closing with the question as to whether the conformants intended to remain true to the Evangelical Church, which meant the Augsburg Confession of 1530, endorsed by Martin Luther. 'I and my brother', Ernest declared for both, 'are determined to remain faithful to the acknowledged truth'"Weintraub, S., Uncrowned King: The Life of Prince Albert, p70, "On 31 March they had gone to observe the Pope's Easter blessing of the crowds in St Peter's Square 'from the balcony, amidst the ringing of bells, firing of cannon, and military music'. It was, Albert wrote to Lowenstein, 'really a most imposing scene', althgouth it 'savoured strongly of idolatry'. ...His Lutheran training at odds with Roman ritual and trappings, Albert also thought...that the Pope looked 'like a Pagoda'" Since the monarch of England cannot (even today), by law, be a Roman Catholic, and forming familial royal bonds was historically deemed necessary at times to form alliances (and prevent war) between countries, there was a natural tendency for British princes/princesses to wed Lutheran or Reformed (and therefore, not Roman Catholic) royals from the houses of Germany, the Netherlands and Scandinavia. Also, a general agreement on doctrine between the Anglican and Lutheran traditions has helped relations, at least between the mainstream movements. Also, the fact that both still retain a strong liturgical tradition has helped immensely, since they are essentially the only Western churches outside of Roman Catholicism which have maintained official liturgies; indeed, the liturgies of both bodies are often nearly identical in wording to each other (as is the Roman Catholic Mass) and, thus provide a familiar bond between members who visit between denominations.

In the late 20th century, the Porvoo Communion was formed, bringing the Anglican churches of England, Scotland, Wales, and Ireland and the Episcopal churches of Portugal and Spain into full communion with the Lutheran Church in Great Britain, the Lutheran churches of the Scandinavian countries (Iceland, Denmark, Finland, Norway, and Sweden), and the Lutheran churches of the Baltic countries (Estonia, Latvia, and Lithuania). In 2001, the Anglican Church of Canada and the Evangelical Lutheran Church in Canada achieved full communion through the Waterloo Declaration,Anglican Church of Canada news release as did the Episcopal Church in the United States and the Evangelical Lutheran Church in America under the joint document Called to Common Mission.Episcopal Life Archives

In addition, full communion agreements have been reached between various ecclesiastical provinces and smaller denominations such as the Old Catholic Church after the Bonn Agreement of 1931.

Other Protestant denominations

Historical Anglicanism "followed the major continental Reformers in their doctrine of the true church, identifiable by the authentic ministry of word and sacrament, in their rejection of the jurisdiction of the pope, and in their alliance with the civil authority ('the magistrate')". The Church of England historically considered itself "Protestant and Reformed" and recognized as true churches the Continental Reformed Churches, participating in the Synod of Dort in 1618–1619.

Movements toward full communion between the Anglican Church of Canada and the United Church of Canada, as well as between the Church of England and the Methodist Church of Great Britain, were both derailed because of the issue of episcopacy, specifically, apostolic succession. The same problem applies to the Churches Uniting in Christ initiative in the United States. This, as well as Anglican stands on certain social issues such as the ordination of priests and bishops in public same-sex relationships and the practice of blessing gay unions, has likewise hindered dialogue between Anglicans and conservative evangelical Protestant denominations. This has not prevented a range of reports by bilateral commissions producing descriptions of converging theology and practice however, such as Conversations around the World (2005), a report of conversations between the representatives of the Anglican Communion and the Baptist World Alliance. In the Indian subcontinent, most Anglican churches have entered into formal union with other Protestant denominations, with the resulting United Protestant churches being a part of multiple communions, including the Anglican Communion and World Communion of Reformed Churches for example. These agreements, which date from the 1940s and 1950s, led to the creation of the Church of North India, the Church of South India, the Church of Pakistan and the Church of Bangladesh. The united churches maintain an episcopal and synodical structure and consecrate bishops in apostolic succession while incorporating distinctives from other traditions such as that of the Moderator, which comes from Presbyterianism. As a percentage of the total population in the region, these united churches are not significant, but aside from Bangladesh, they are numerically very substantial.

Those that did not join with the union agreements in the Indian subcontinent retained the name Anglican Church of India, or adopted a similar name containing "Anglican". The total membership of these churches has been estimated at 800,000. Most have recently entered into communion with churches of the Continuing Anglican Movement and have North American parishes.

Outside of Asia, direct consultations with other Protestant churches apart from Lutherans have, for the most part, been less fruitful. Movements toward full communion between the Anglican Church of Canada and the United Church of Canada were derailed because of the issue of episcopacy and the mutual recognition of ordained ministry (specifically, apostolic succession). The same issue blocked the first attempt at a covenant between the Church of England and the Methodist Church of Great Britain, but such a covenant was eventually signed in 2003. This issue also has held back the Churches Uniting in Christ initiative in the United States.

The issue of apostolic succession, as well as the willingness of some North American dioceses to offer partnership blessings and priestly ordination to people in same-sex sexual relationships, have hindered dialogue between Anglicans and other evangelical Protestant denominations.

Orthodox churches

Dialogue has also been fruitful with the Orthodox churches.

In 1922 the Ecumenical Patriarch of Constantinople Meletius IV recognised Anglican orders as valid. He wrote: "That the orthodox theologians who have scientifically examined the question have almost unanimously come to the same conclusions and have declared themselves as accepting the validity of Anglican Orders." In 1923, the synod of Constantinople affirmed the Patriarch's decision. Following the decision of Constantinople, the autocephalous Orthodox churches of Alexandria, Cyprus, Greece, Jerusalem, and Romania conditionally recognised that Anglican orders preserved apostolic succession. The reason for this conditionality was that from the Eastern Orthodox point of view, no Holy Orders outside of their own church could truly be valid without a complete church reunion.