 A devout Unitarian, he taught at the Harvard Divinity School and most of his writings deal with religious figures and issues.In 1882, he was appointed to a Harvard chair as Winn Professor of Ecclesiastical History, the first such professorship bestowed by the Winn financial endowment.In 1884, Emerton became one of the founders of the oldest and largest historians' society in the United States, the American Historical Association.