
In 1865 he was called to the Chair of Exegetical Theology in Knox College, Toronto, became principal in 1873, and led the college into full affiliation with University of Toronto. He remained as principal until his death in 1904. The present Knox College building, shown, was completed in 1914.
In 1875, as moderator of the General Assembly of the Canada Presbyterian Church, he was involved in the negotiations which united the Free Church and Kirk in the Presbyterian Church in Canada. Caven was a strong opponent of the Jesuits' Estates Act of 1888 and of denominational schools in Manitoba in the 1890s. At the same time, he was also a strong advocate of interdenomination Protestant union.