Lyndon is a town in Caledonia County, Vermont, United States. The population was 5,448 at the 2000 census. Lyndon is the home of Lyndon State College. The town contains one incorporated village, Lyndonville and three unincorporated villages: Lyndon, Lyndon Center, and East Lyndon. Lyndon is the second-most populous town in the Northeast Kingdom; only neighboring St. Johnsbury is larger.