Northfield is a town in Franklin County, Massachusetts, United States. Northfield was first settled in 1673. The population was 2,866 at the 2020 census. It is part of the Springfield, Massachusetts Metropolitan Statistical Area. The Connecticut River runs through the town, dividing West Northfield from East Northfield and the village of Northfield, where the town hall is located.

Franklin County is a nongovernmental county located in the northwestern part of the U.S. state of Massachusetts. As of the 2020 census, the population was 71,029, which makes it the least-populous county on the Massachusetts mainland, and the third-least populous county in the state. Its traditional county seat and most populous city is Greenfield. Its largest town by area is New Salem. Franklin County comprises the Greenfield Town, MA Micropolitan Statistical Area, which is included in the Springfield-Greenfield Town, MA Combined Statistical Area.