The Plymouth Brethren is a widely used, but unofficial, designation for a loose grouping of churches with early nineteenth-centry roots in the British Isles. Within these churches, the common terminology is simply "Brethren" or "Christian Brethren," but they are to be distinguished from Brethren churches associated with the Pietist movement [...].

Similar to the Restorationist bodies in the U.S., the early Brethren envisioned a basis for Christian unity by forsaking denominational structures and names in order to meet simply as Christians.

The autonomy of the local congregation is another feature of the movement, coupled with the doctrinal understanding that a church is not a building, but the gathering of people who meet there.

The weekly hour-long "remembrance meeting" is probably the surest way to identify a Brethren assembly. The centrality of the Communion service is characteristic: In according with the meaning of "priesthood of all believer," the service is unstructured. Brethren have consistenly refused to restrict the administration of baptism of the Lord's Supper to ordained ministers, thus effectively eliminating a clergy/laity distinction and the traditional concept of ordination. Anyone, many or woman, in the assembly is free to speak. A preacher may serve full-time with a congregation, but will not be identified as clergy or given control over the congregation.

The Brethren are committed to all the fundamentals of conservatice Christianity, including the verbal inspiration of Scripture. They emphasize gospelc preaching and the necessity for personal conversion. Except for the weekly breaking of bread and the absence of collections at other meetings, their services are much like those of evangelical Baptist or free and Bible churches.

Among American evangelicals, Brethren have had an influence out of proportion to their number. Their pre-millenial theology helped to shape evangelicalism, especially in the proliferation of independent churches and mission boards. Many have responded to the Brethren emphasis on plurality of leadership and participatory worship in the local church.
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As a result of a division in England in 1848, there are two basic types of assemblies, commonly known as exclusive and open. Led in the beginning by John Nelson Darby (1800-82), the exclusive assemblies produced most of the movement's well-known Bible teachers, such as William Kelly and others. They operated on the premise that disciplinary action taken by one assembly was binding on all. As a result, once started, a division continued, until by the end of the century the exclusive Brethren were divided into seven or eight main groups. Recent mergers have reduced that number somewhat, and an important American group has merged with the open assemblies.

Open assemblies were led by George Muller (1805-95), well known for his ophanages and life of faith.