Plainfield is a town in Otsego County, New York, United States. The population was 915 at the 2010 census.

Otsego County is a county in the U.S. state of New York located within the Mohawk Valley Region. As of the 2020 census, the population was 58,524. The county seat is Cooperstown. The county's population center is Oneonta. The name Otsego is from a Mohawk or Oneida word meaning "place of the rock." The county is part of the Mohawk Valley region of the state.