Forest Grove is a city in Washington County, Oregon, United States, 25 miles (40 km) west of Portland. Originally a small farm town, it is now primarily a commuter town in the Portland metro area. Settled in the 1840s, the town was platted in 1850, then incorporated in 1872, making it the first city in Washington County. The population was 21,083 at the 2010 census, an increase of 19.1% over the 2000 figure (17,708).

Washington County is one of 36 counties in the U.S. state of Oregon and part of the Portland metropolitan area. The 2020 census recorded the population as 600,372, making it the second most populous county in the state and most populous "Washington County" in the United States. Hillsboro is the county seat and largest city, while other major cities include Beaverton, Tigard, Cornelius, Banks, Gaston, Sherwood, North Plains, and Forest Grove, the county's oldest city. Originally named Twality when created in 1843, the Oregon Territorial Legislature renamed it for the nation's first president in 1849 and included the entire northwest corner of Oregon before new counties were created in 1854. The Tualatin River and its drainage basin lie almost entirely within the county, which shares its boundaries with the Tualatin Valley. It is bordered on the west and north by the Northern Oregon Coast Range, on the south by the Chehalem Mountains, and on the north and east by the Tualatin Mountains, or West Hills.