Flandreau Indian School (FIS), previously Flandreau Indian Vocational High School, is an boarding school for Native American children (primarily Lakota) in unincorporated Moody County, South Dakota, adjacent to Flandreau. It is operated by the Bureau of Indian Education (BIE) and is off-reservation. It is one of four such off-reservation boarding schools directly operated by the BIE. It offers grades 9-12. Established in 1872 as a Presbyterian mission school, it is the oldest continuously operating Indian boarding school in the United States.