The six official languages of the United Nations, used in intergovernmental meetings and documents, are Arabic, Chinese, English, French, Russian and Spanish.The Secretariat uses two working languages, British English and French.

Five of the official languages were chosen when the UN was founded (the languages of the permanent members of the Security Council, plus Spanish, which was the official language of the largest number of nations at the time). Arabic was added in 1973; the number of Arabic-speaking member states had increased substantially since 1945, and the 1973 oil crisis provided the catalyst for the addition. A "documentary language" status was granted for use of the German language in 1974, allowing for translation of important documents (funded, however, by the German-speaking member countries).

The UN standard for English language documents (United Nations Editorial Manual) follows British usage and Oxford spelling (en-gb-oed). The UN standard for Chinese (Standard Mandarin) changed when the Republic of China (Taiwan) was succeeded by the People's Republic of China in 1971. From 1945 until 1971 traditional characters were used, and since 1972 simplified characters have been used.