Presbyterian church formed in 1900 as the result of the union between the Free Church of Scotland and the United Presbyterian Church (qq.v.). A series of unanimous decisions brought the United Presbyterian Church into the union. In the Free Church, however, a small minority strongly opposed union. They claimed to be the authentic Free Church and engaged in legal action to have their position and their sole right to the property of the Free Church recognized and declared. In the Scottish courts in 1901 and 1902, the verdict was unanimously against the claim and for the United Free Church, but in 1904 the House of Lords reversed this decision. The situation thus created was so difficult that government action followed. After an investigation a commission was set up that assigned to the United Free Church all the properties that the Free Church was not able to use.

Meanwhile, the turmoil had helped to weld the United Free Church into a closer unity as a vital, active church. From 1900 to 1929 it supported three colleges, in Aberdeen, Edinburgh, and Glasgow, and many of these schools' professors were among the notable scholars of the period. What has come to be regarded as the first milestone in the Protestant Ecumenical Movement, the World Missionary Conference of 1910, was housed in the General Assembly Hall of the United Free Church in Edinburgh.

When the United Free Church united with the Church of Scotland in 1929, a small minority of its members chose to remain outside. See also Scotland, Church of.