Stewartstown is a town in Coös County, New Hampshire, United States. The population was 813 at the 2020 census, down from 1,004 at the 2010 census. It includes the village of West Stewartstown and is part of the Berlin, NH-VT Micropolitan Statistical Area.

Coös County or Coos County is a county in the U.S. state of New Hampshire. As of the 2020 census, the population was 31,268, making it the least-populated county in the state. The county seat is Lancaster.