In 1861 the first step towards the consolidation of Presbyterianism throughout New Zealand was taken by Auckland presbytery when the Rev. David Bruce was instructed to write to the other presbyteries and to the “scattered brethren” suggesting that a conference be held with a view to forming a church which would embrace all New Zealand. The presbytery of Otago agreed and the result was a Unity Conference in Dunedin in November 1861. This conference agreed on a basis of union for submission to a convocation of the Church to be held in Auckland in 1862. The convocation was duly held and, after making some alterations to the basis of union, it constituted itself the General Assembly of the Presbyterian Church of New Zealand. But the presbytery of Otago refused to recognise the union and in 1866 the Synod of Otago and Southland (Southern Church) was constituted. The failure of the union movement of the sixties meant that the union of the Northern and Southern Churches was postponed until 1901 when, under the leadership of Dr James Gibb, the General Assembly of the Presbyterian Church of New Zealand was brought into being. Since the union, the Presbyterian Church of New Zealand has grown in influence and in membership. A feature of this growth has been rapid development in the North Island but much slower growth in the South. One result of the change in population balance has been that the median line of Presbyterianism in New Zealand has moved progressively northwards.

The 1964 Assembly statistics give the following figures concerning the Presbyterian Church of New Zealand:

• 24 presbyteries (the Maori synod having presbyterial powers).

• 446 parishes.

• 806 church buildings.

• 566,174 persons under pastoral care.

• 90,542 communicants.

• 73,695 Sunday school scholars.

• 20,427 Bible class members.

• A gross revenue of £1,639,056.