Hatfield was founded in 1660 on land granted to General Daniel Dennison and Governor William Bradford. It was formally incorporated as a town in 1670 and has a Board of Selectmen and annual town meeting.
As a center for agriculture the region produced cattle, sheep, corn, and tobacco. At first their relations with the local Indians were very welcoming on both sides. On October 16, 1675 a substantial part of the town was destroyed in King Philip's War, and surviving settlers sought refuge in Springfield.
During the American Revolution, Hatfield was an important source of supplies and men for the rebels. In 1786 the town was used as an assembly area for the discontented who became involved in Shays' Rebellion.
One family supplied many of Hatfield's physicians for generations. The Hastings family, descendants of English Puritan immigrant Thomas Hastings, was originally settled at Watertown, but within a generation members of the family had relocated to Hatfield, where they produced a succession of Hatfield physicians, including Dr. Thomas Hastings (1652–1712); Dr. Thomas Hastings (1679–1728); Dr. Waitstill Hastings (1714–1748); and Dr. John Hastings (1765–1845). The first Thomas Hastings, aside from serving as physician to Hatfield and surrounding communities, was also the town's first schoolteacher. He authored a contemporary account of the devastating Indian attack on nearby Deerfield in 1704.