The Plain Farm House is an historic house at 108 Webster Avenue in Providence, Rhode Island. It is a 2-1/2 story wood frame structure, five bays wide, with a central entry flanked by sidelight windows and topped by a semi-elliptical fan. The house was probably built in the early 19th century, based on its Federal styling, and on the opening of the nearby Norwick Pike (now Plainfield Street, Rhode Island Route 14) in 1803. At the time of its construction the area was part of Johnston, and was annexed to Providence in 1898. Once the main house of a large farm, it is now surrounded by residential development.