The majority of Iranian population speak Persian, which is also the official language. Others include speakers of a number of other Iranian languages within the greater Indo-European family, and languages belonging to some other ethnicities living in Iran. In northern Iran, mostly in Gilan and Māzandarān, the Gilaki and Mazandarani languages are widely spoken, both having affinities to the neighboring Caucasian languages. In parts of Gilan, the Talysh language is also spoken, which stretches up to the neighboring Republic of Āzerbāijān zerbāijān .

Varieties of Kurdish is widely spoken in the province of Kurdistan and nearby areas. In Khuzestan, several distinct varieties of Persian are spoken. Lurish and Lari are also spoken southern Iran. Azeri Turkish, which is by far the most spoken language after Persian, as well as a number of other Turkish languages and dialects, is spoken in various regions of Iran, especially in the region of Āzerbāijān. Notable minority languages in Iran include Armenian, Georgian, Neo-Aramaic, and Arabic. Khuzi Arabic is spoken by the Arabs in Khuzestan, as well as the wider group of Iranian Arabs.

Circassian was also once widely spoken by the large Circassian minority, but, due to assimilation over the many years, no sizable number of Circassians speak the language anymore. Percentages of spoken language continue to be a point of debate, as many opt that they are politically motivated; most notably regarding the largest and second-largest ethnicities in Iran, the Persians and Āzerbāijān Percentages are given by the CIA’s World Factbook include 53% Persian, 16% Āzerbāijān Turkish, 10% Kurdish, 7% Mazenderani and Gilaki, 7% Lurish, 2% Turkmen, 2% Balochi, 2% Arabic, and 2% the remainder Armenian, Georgian, Neo-Aramaic, and Circassian.