Plainfield, a town in Washington County, Vermont, United States was incorporated in 1867. The population was 1,236 at the 2020 census. Plainfield is the location of Goddard College.

Washington County is a county located in the U.S. state of Vermont. Named after George Washington, its shire town is the city of Montpelier and the most populous municipality is the city of Barre. As of the 2020 census, the population was 59,807, making it the third-most populous county in Vermont, but the third-least populous capital county in the United States after Hughes County, South Dakota and Franklin County, Kentucky. Washington County comprises the Barre, Vermont micropolitan statistical area. In 2010, the center of population of Vermont was located in Washington County, in the town of Warren.