This dissertation examines the life and work of the Reverend John Callender placed within the context of the emergence of toleration in New England in the later seventeenth, and early eighteenth centuries. A survey of Colonial American church history reveals the persistent theme of persecution of outside groups by the Puritans, but the emergence of religious toleration is understudied. Callender benefited from Puritan and Baptist influences, and his life and work serve as an example of toleration. New England Puritanism was the culmination of different shades of puritan piety that travelled from England: nomistic, evangelical, rationalistic, and mystical. The Puritans modeled their settlements in a pietistic Calvinistic covenantal model. Their strict adherence to this model led them to enact laws in order to punish dissenters. From the Puritans' perspective, they were not persecuting, but were preserving God's commandments. The pinnacle of persecution came in 1651 when Baptists and Quakers were severely punished for their dissent. However, institutional persecution of this sort eventually declined, and toleration began to emerge due to a variety of factors including: pressure from the British government and its influential citizens; the loosening of the ties between churches and government; the fracturing of closely-knit towns, due to the migration of farmers to open spaces; and the persistent migration of dissenting groups into New England towns. In the early part of the eighteenth century, the Baptists won the approval of Congregationalists after having suffered many decades of persecution since their founding in 1665. Cotton Mather would eventually initiate cooperation with the Baptists when he invited them to a joint worship service with Congregationalists in 1714. Four years later in 1718, Mather led the historic ordination service for Elisha Callender, a Baptist. Thus began the cooperation of Baptists and Congregationalists beginning in the eighteenth century. John Callender, Elisha's nephew, continued the practice of tolerance as embodied in his ministry and works. His friendships with notable Congregationalists, his ministry to Baptists and Congregationalists alike, and his writings, provide evidence of his efforts toward toleration. Additionally, Callender's Historical Discourse, an authoritative history of Rhode Island for about a century after its writing, contributed to the work of Isaac Backus and to the discipline of history, specifically Providential history and the Whig interpretation of history.