The United Church of Christ (UCC) is a mainline Protestant Christian denomination principally in the United States, generally considered to be within the Reformed tradition, and formed in 1957 by the union of two denominations, the Evangelical and Reformed Church and the Congregational Christian Churches.

According to our 2006 yearbook, the United Church of Christ has approximately 1.2 million members and is composed of approximately 5,633 local congregations.

Although similar in name, the UCC denomination is culturally and historically distinct from the Churches of Christ, a loose affiliation of conservative congregations that arose primarily from the Restorationist movements of the 19th-century American frontier.

The UCC uses four words to describe itself: Christian, Reformed, Congregational and Evangelical. The church's diversity and adherence to covenantal polity (rather than government by regional elders or bishops) give individual congregations a great deal of freedom in the areas of worship, congregational life, and doctrine.

The motto of the United Church of Christ comes from John 17:21: "That they may all be one."

The UCC came into being in 1957 with the union of two Protestant denominations: the Evangelical and Reformed Church and the Congregational Christian Churches. Each of these was, in turn, the result of a union of two earlier traditions.

The Congregational Churches were organized when the Pilgrims of Plymouth Plantation (1620) and the Puritans of the Massachusetts Bay Colony (1629) acknowledged their essential unity in the Cambridge Platform of 1648.

The Reformed Church in the United States traced its beginnings to congregations of German settlers in Pennsylvania founded from 1725 on. Later, its ranks were swelled by Reformed immigrants from Switzerland, Hungary and other countries.

The Christian Churches sprang up in the late 1700s and early 1800s in reaction to the theological and organizational rigidity of the Methodist, Presbyterian and Baptist churches of the time.

The Evangelical Synod of North America traced its beginnings to an association of German Evangelical pastors in Missouri. This association, founded in 1841, reflected the 1817 union of Lutheran and Reformed churches in Germany.

Through the years, other groups such as American Indians, Afro-Christians, Asian Americans, Pacific Islanders, Volga Germans, Armenians, and Hispanic Americans have joined with the four earlier groups. In recent years, Christians from other traditions, including the Roman Catholic Church, have found a home in the UCC, and so have gay and lesbian Christians who have not been welcome in other churches. Thus the United Church of Christ celebrates and continues a broad variety of traditions in its common life.