This chapter explores the relationship between the animating principle of colonial Connecticut—Puritan Congregationalism—and the colony’s laws. Part I chronicles how central Puritan Congregationalism was in the organic law, statutory law, and common law of the River Colony at which Connecticut was originally planted. Part II investigates the law of the New Haven Colony, a separate community settled in 1638 that joined with the River Colony in 1665 to create a unified Connecticut Colony. Part III examines the law of the unified Connecticut Colony and endeavors to discern when Connecticut’s laws began to deviate from Puritan Congregationalism. Part IV concludes the chapter by assessing the events that led to the official demise in the Connecticut Constitution of 1818 of Puritan Congregationalism as the animating principle of Connecticut. As will be seen, the law of colonial Connecticut eventually came to reflect the idea of religious toleration sweeping, albeit unevenly and imperfectly, across the larger Atlantic World.