The languages have similar sound systems but differ significantly in terms of grammar. They are not mutually intelligible, even though many works often refer to all of the speakers of these languages as Maidu. The Chico dialects are little known due to scanty documentation, so their precise genetic relationship to the other languages probably cannot be determined (Mithun 1999).
Three of the languages went extinct by approximately the year 2000. Konkow was reported to have 3 elderly speakers in 2007.
Maiduan is often considered in various Penutian phylum proposals. It was one of the original members of California Penutian (the Penutian "core").