Siouan languages, family of languages in North America spread primarily across the Great Plains, extending from Canada to Mississippi to North Carolina. The languages belonging to this family are classified as follows. The Catawban branch (formerly spoken in North and South Carolina) is the most divergent—i.e., the first to break off. Several of the languages are extinct (marked in the classification below with an asterisk [*]), and the rest are endangered.

• Siouan

  • Missouri River

    • Hidatsa
    • Crow

  • Mandan

    • Mandan

  • Dakotan

    • Sioux (Dakota-Lakota)
    • Assiniboine
    • Stoney

  • Dhegihan

    • Omaha-Ponca
    • Osage
    • *Kansa
    • *Quapaw

  • Chiwere-Winnebago

    • Chiwere
    • Winnebago (Ho-Chunk, Hochank)

  • Southeastern

    • *Ofo
    • *Biloxi
    • *Tutelo
• Catawban

  • *Catawba
  • *Woccon

The Macro-Siouan hypothesis that proposed grouping Siouan, Caddoan, Iroquoian, and Yuchi in a large superfamily (or phylum) is now essentially abandoned.