The Reformed Church in America (RCA) is a mainline Reformed Protestant denomination in Canada and the United States. It has about 84,957 members. From its beginning in 1628 until 1819, it was the North American branch of the Dutch Reformed Church.

The mainline Protestant churches are a group of Protestant denominations in the United States and in some cases in Canada largely of the theologically liberal or theologically progressive persuasion that contrast in history and practice with the largely theologically conservative Evangelical, Fundamentalist, Charismatic, Confessional, Confessing Movement, historically Black church, and Global South Protestant denominations and congregations. Some make a distinction between "mainline" and "oldline", with the former referring only to denominational ties and the latter referring to church lineage, prestige and influence. However, this distinction has largely been lost to history and the terms are now nearly synonymous.