While the term Reformed has sometimes been taken to include all the Protestant churches which have accepted the principles of the Reformation, it is used here in the more accurate sense to refer specifically to church bodies which have theological and historical roots in the French and Swiss-led Reformation (Jean Calvin, Ulrich Zwingli, Bullinger, etc.). The primary presupposition of the Reformed churches is that the risen Christ is the only head of the church. Thus there is no stress on a special elite person or group that has received through direct revelation or by the laying on of hands extraordinary powers of authority. Doctrines are traditionally governed by such principles as Sola Scriptura, salvation by grace through faith in Jesus Christ, God's sovereignty, and the calling to be agents of transformation in the world. Worship is usually simple, orderly and dignified, with an emphasis upon the hearing and preaching of the word of God. Few Reformed and Presbyterian churches have weekly celebration of the eucharist; monthly eucharistic celebrations are more common. The level of education required for the Presbyterian or Reformed minister is traditionally high.
The Reformed churches generally adhere, with some variations, to a form of ecclesiastical polity in which the church is led by teaching elders (ordained pastors) and ruling elders or presbyters (lay persons) who are organized in various "courts". The courts include the local church level (session or its equivalent), the regional church level (Presbytery, classis or an equivalent title), the wider regional or national level (the synod) and the national or highest autonomous level (general assembly or general synod). Synods consist of members of several presbyteries within a large area and in some cases constitute the final legislative body. Usually the general assembly or general synod is the supreme legislative and administrative body. Proponents of this governing structure in the 16th and 17th centuries did not regard it as an innovation but as a rediscovery of the apostolic model found in the New Testament. According to Calvin, the Primitive Church had four different offices: pastor, doctor or teacher, deacon, and presbyter or elder. He recognized, however, that other offices might be adopted.
The Reformed family has a broad spectrum. It has churches from the historic Reformation era, which now share much in common with other mainline Protestants. It also has churches from pietist and separation movements in the 18th and 19th centuries, whose recommitments to Scripture and the Reformed confessional documents continue to influence their values today. In the 20th century some were also influenced by the Evangelical and Pentecostal traditions. As a result there are four international groupings of the Reformed family.