Deerfield is a town in Franklin County, Massachusetts, United States. Settled near the Connecticut River in the 17th century during the colonial era, the population was 5,090 as of the 2020 census. Deerfield is part of the Springfield, Massachusetts Metropolitan Statistical Area in western Massachusetts, lying 30 miles (48 km) north of the city of Springfield.

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.