Martha Simon, Last of the Narragansetts, oil painting from 1857 by Albert Bierstadt.
Traditionally the tribe spoke the Narragansett language, a member of the Algonquian language family. The language became almost entirely extinct during the Narragansetts' centuries of living within the larger English-majority society, through forced assimilation.
The tribe has begun language revival efforts, based on early-20th-century books and manuscripts, and new teaching programs. The Narragansett spoke a "Y-dialect", similar enough to the "N-dialects" of the Massachusett and Wampanoag to be mutually intelligible. Other Y-dialects include the Shinnecock and Pequot languages spoken historically by tribes on Long Island and in Connecticut, respectively.
According to Dr. Frank Waabu O'Brien, who has taught the language for the Aquidneck Indian Council, "Narragansett was understood throughout New England." He states that "Scholars refer to Massachusett and Narragansett as dialects of the same language," and has created a diagram of the relationships between the languages as described in their source documentation  as well as instructional materials. A Facebook page entitled "Speaking Our Narragansett Language" has provided alphabet and vocabulary of the language.
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^Lewis, M. Paul (ed.), 2009. Ethnologue: Languages of the World. 16th edition. Dallas: Summer Institute of Linguistics
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**"Lesson Two in Narragansett Tongue." The Narragansett Dawn 1 (June 1935): 14-5.
**"Lesson No. Three in Narragansett Tongue." The Narragansett Dawn 1 (July 1935): 10.
**"The Narragansett Tongue- Lesson 4.” The Narragansett Dawn 1 (August 1935): 88-9.
**"The Narragansett Tongue- Lesson 5." The Narragansett Dawn 1 (September 1935): 122-4.
**"Narragansett Lesson No. 6." The Narragansett Dawn 1 (October 1935): 138-9.
**"Narragansett Tongue- Lessons 7 and 8." The Narragansett Dawn 1 (December 1935): 185-7.
**"Narragansett Tongue- Lesson 9." The Narragansett Dawn 1 (January 1936): 204.
**"Narragansett Tongue- Lesson 10." The Narragansett Dawn 1 (February 1936): 232.
**"Narragansett Tongue- Lesson 11." The Narragansett Dawn 1 (March 1936): 259-60.
**"Narragansett Tongue- Lesson 12." The Narragansett Dawn 1 (April 1936): 287.
**"Narragansett Tongue- Lesson 13." The Narragansett Dawn 2 (May 1936): 5.
**"Narragansett Tongue- Lesson 14." The Narragansett Dawn 2 (June 1936): 29.
**"Narragansett Words." The Narragansett Dawn 2 (October 1936): 6.
Moondancer and Strong Woman (2000). Indian Grammar Dictionary for N Dialect: A Study of A Key into the Language of America by Roger Williams, 1643. Newport, RI: Aquidneck Indian Council. .
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Rider, Sidney S. (1904). Map of the Colony of Rhode Island: Giving the Indian Names of Locations and the Locations of Great Events in Indian History with Present Political Divisions Indicate. In The Lands of Rhode Island as They Were Known to Caunounicus and Miatunnomu When Roger Williams Came. Providence, Rhode Island: Sidney S. Rider.
Strong Heart and Firefly Song of the Wind Sekatau. ”The Nahahigganisk Indians". Bicentential 1976, pp. 1-17.
Williams, Roger (1643). A Key into the Language of America:, or, an Help to the Language of the Natives in that Part of America called New-England. Together, with Briefe Observations of the Customes, Manners and Worships, etc. of the Aforesaid Natives, in Peace and Warre, in Life and Death. On all which are added Spirituall Observations, General and Particular by the Author of chiefe and Special use (upon all occasions) to all the English Inhabiting those parts; yet pleasant and profitable to the view of all men. London: Gregory Dexter. [Reprinted, Providence: Narragansett Club, 1866, J. H. Trumbull [Ed.] & Fifth Edition (reprinted Applewood Books, nd.)].
Wojciechowski, Franz L.The Search for an Elusive 1765 Narragansett Language Manuscript. International Journal of American Linguistics 65(2):228-232 (1999).