Sunderland is a town in Franklin County, Massachusetts, United States, part of the Pioneer Valley. The population was 3,663 at the 2020 census. It is part of the Springfield, Massachusetts Metropolitan Statistical Area. Sunderland was first settled in 1713 and was officially incorporated in 1718. It was first known as Swampfield, a name which is now honored by Swampfield Road, but the name was changed to attract more residents.