Mansfield is a town in Tolland County, Connecticut, United States. The population was 20,720 at the 2000 census. Mansfield was incorporated in October 1702 from the Town of Windham, in Hartford County. When Windham County was formed on 12 May 1726, Mansfield then became part of that county. A century later, at a town meeting on 3 April 1826, selectmen voted to ask the General Assembly to annex Mansfield to Tolland County. That occurred the following year.