Grafton is a town in Worcester County, Massachusetts, United States. The population was 19,664 at the 2020 census. The town consists of the North Grafton, Grafton, and South Grafton geographic areas, each with a separate ZIP Code. Incorporated in 1735, the town is home to a Nipmuc village known as Hassanamisco Reservation, the Willard House and Clock Museum, Community Harvest Project, and the Tufts University Cummings School of Veterinary Medicine.