Plainfield is a village in Will and Kendall counties, Illinois, United States. The population was 39,581 at the 2010 census and an estimated 44,308 in 2019.
The village includes land in Will County's Plainfield and Wheatland townships, as well as Na-Au-Say and Oswego townships in Kendall County. With the growth in the Chicago suburbs in the 1990s and 2000s, the village has seen a population increase, from 4,500 in 1990 to 28,000 in 2000 to nearly 45,000 in 2016. It is between the cities of Naperville and Joliet.
The village has established a community Preservation Commission and historic preservation ordinance. It is the home of the Lake Renwick Preserve, a county forest preserve used for birdwatching and other activities. Located south of Village Hall is Settlers' Park, which includes a lake, war monument, open space, and more. The park presents outdoor concerts to the public in the summer.
The area was called "Walkers' Grove" until it was platted as "Plainfield" in 1841. It was originally settled by a large community of Potawatomi people, and the land was later bequeathed to the United States as part of the Treaty of St. Louis (1816) with the Council of the Three Fires.