Colchester is a town in Chittenden County, Vermont, United States. As of the 2020 census, the population of Colchester was 17,524. It is the third-most populous municipality and most populous town in the state of Vermont. Colchester borders Burlington, Vermont's most populous municipality and is part of its metropolitan area. The town is directly to Burlington's north on the eastern shore of Lake Champlain, to the west of the Green Mountains. The Vermont National Guard is based in the town, and it is also home to Saint Michael's College and the Vermont campus of Southern New Hampshire University.