Established in 1560, the Church of Scotland was the only ecclesiastical body established by law in Scotland. The General Assembly was Scotland's only national legislative assembly. It met every May and the moderator, who presided over the General Assembly, was elected annually by the delegates.

By 1901 the membership of the Church of Scotland had reached 662,000. Its leading competitors included the Free Church of Scotland (288,000) the United Presbyterian Church (194,000) and the Scottish Episcopal Church (47,000). There were also Baptists and Methodists and a growing number of Roman Catholics, composed mainly of Irish immigrants, settling in industrial centres such as Glasgow.