Samoan (Gagana fa'a Sāmoa or Gagana Sāmoa — IPA: [ŋaˈŋana ˈsaːmʊa]) is the language of the Samoan Islands, comprising the independent country of Samoa and the United States territory of American Samoa. It is an official language—alongside English—in both jurisdictions. Samoan, a Polynesian language, is the first language for most of the Samoa Islands' population of about 246,000. With many Samoan people living in other countries, the total number of speakers worldwide is estimated at 370,000. The language is notable for the phonological differences between formal and informal speech as well as a ceremonial form used in Samoan oratory.

Samoan is a member of the Austronesian family, and more specifically the Samoic branch of the Polynesian subphylum. It is closely related to other Polynesian languages with many shared cognate words such as ali'i, 'ava, atua, tapu and numerals as well as in the name of gods in mythology.

Linguists differ somewhat on the way they classify Samoan in relation to the other Polynesian languages. The "traditional" classification, based on shared innovations in grammar and vocabulary, places Samoan with Tokelauan, the Polynesian outlier languages and the languages of Eastern Polynesia, which include Rapanui, Māori, Tahitian and Hawaiian. Nuclear Polynesian and Tongic (the languages of Tonga and Niue) are the major subdivisions of Polynesian under this analysis. A revision by Marck reinterpreted the relationships among Samoan and the outlier languages. In 2008 an analysis, of basic vocabulary only, from the Austronesian Basic Vocabulary Database is contradictory in that while in part it suggests that Tongan and Samoan form a subgroup, the old subgroups Tongic and Nuclear Polynesian are still included in the classification search of the database itself.