Old Catholic Church

The terms Old Catholic Church, Old Catholics, Old-Catholic churches, or Old Catholic movement, designate "any of the groups of Western Christians who believe themselves to maintain in complete loyalty the doctrine and traditions of the undivided church but who separated from the See of Rome after the First Vatican Council of 1869–70".

The expression Old Catholic has been used from the 1850s by communions separated from the Catholic Church over certain doctrines, primarily concerned with papal authority and infallibility. Some of these groups, especially in the Netherlands, had already existed long before the term. The Old Catholic Church is separate and distinct from Traditionalist Catholicism.

Two groups of Old Catholic churches are: the Union of Utrecht (UU, not to be confused with Unitarian Universalism) and the Union of Scranton (US). Neither group is in full communion with the Holy See. Member churches of the Union of Utrecht are in full communion with the Anglican Communion as well as the Evangelical Lutheran Church of Sweden and the Philippine Independent Church and many UU churches are members of the World Council of Churches. Other churches which claim to be Old Catholic yet are not members of the Union of Utrecht or Union of Scranton are Independent Old Catholics; within the independent sacramental movement, Independent Old Catholics do not consider recognition by Utrecht as a necessary litmus test.

Both mainstream groups trace their beginning to the 18th century when members of the See of Utrecht refused to obey papal authority and were excommunicated. Later Catholics who disagreed with the Catholic dogma of papal infallibility, as defined by the First Vatican Council (1870), were thereafter without a bishop and joined with the See of Utrecht to form the Union of Utrecht of the Old Catholic Churches. Today, Utrechter Union churches are found chiefly in Germany, Switzerland, the Netherlands, Austria, Poland, and the Czech Republic.

In 2008, the Polish National Catholic Church created the Union of Scranton and separated from the Union of Utrecht. This was done in protest of the older Union's decision to ordain women and bless same-sex marriages. The Nordic Catholic Church later joined the Union of Scranton as well.

In 2020, according to the World Christian Database and World Christian Encyclopedia, published by Edinburgh University Press, there were 4,896,000 Old Catholics worldwide, altogether.