Penutian is a proposed grouping of language families that includes many Native American languages of western North America, predominantly spoken at one time in British Columbia, Washington, Oregon, and California. The existence of a Penutian stock or phylum has been the subject of debate among specialists. Even the unity of some of its component families has been disputed. Some of the problems in the comparative study of languages within the phylum are the result of their early extinction and limited documentation.

Some of the more recently proposed subgroupings of Penutian have been convincingly demonstrated. The Miwokan and the Costanoan languages have been grouped into an Utian language family by Catherine Callaghan. Callaghan has more recently provided evidence supporting a grouping of Utian and Yokutsan into a Yok-Utian family. There also seems to be convincing evidence for the Plateau Penutian grouping (originally named Shahapwailutan by J. N. B. Hewitt and John Wesley Powell in 1894) which would consist of Klamath–Modoc, Molala, and the Sahaptian languages (Nez Percé and Sahaptin).