Siouan languages
Authors who call the entire family "Siouan" distinguish the two branches as "Western Siouan" and "Eastern Siouan" or as "Siouan-proper" and "Catawban". Others restrict the name "Siouan" to the western branch and use the name "Siouan–Catawban" for the entire family. Generally, however, the name "Siouan" is used without distinction.
Siuslaw language
Siuslaw is usually considered to belong to the Penutian phylum, and may form part of an Coast Oregon Penutian subgroup together with Alsea and the Coosan languages.