She is a professor of linguistics at the University of California, Santa Barbara, where she has held an academic position since 1986.
She began her career with extensive fieldwork on Iroquoian languages, especially Mohawk, Cayuga, and Tuscarora, earning her PhD in Linguistics from Yale in 1974 with a dissertation entitled "A Grammar of Tuscarora" (Floyd Lounsbury, dissertation supervisor).
[1] Her work spans a number of linguistic subfields, including morphology, syntax, discourse, prosody, language contact and change, typology, language documentation, and the interrelations among these subfields.
[4] A review on the Linguist List describes the work as "an excellent book to have as a reference" and as containing "an incredible amount of information and illustrative data."
[15] Mithun has taught at many institutions around the world, including Georgetown, La Trobe, Rice, Stanford, SUNY Albany, Amsterdam, Cagliari, Berkeley, Hamburg, UIUC, UNM, Wake Forest, and Yale.