Morse did much toward securing the foundation of Andover Theological Seminary, especially by his successful efforts in preventing the establishment of a rival institution in West Newbury which had been projected by the Hopkinsians (chiefly Samuel Spring and Leonard Woods, with the financial backing of William Bartlett). He participated in the organization of the Park Street Church in Boston in 1808, when all the Congregational churches of that city, except the Old South Church, had abandoned the orthodox faith. In 1805, he established "The Panoplist" for the purpose of illustrating and defending the commonly received orthodoxy of New England, and continued its sole editor for five years. This journal later became "The Missionary Herald".