The official languages of Singapore are English, Mandarin Chinese, Malay and Tamil. Spoken natively by the majority of Singaporeans, English is the de facto main language in daily, governmental, legal, trade and commercial affairs. Among themselves, Singaporeans often speak Singlish, a contact language arising from centuries of contact between Singapore's multi-ethnic and multilingual society and its legacy as a British colony. The Constitution of Singapore designates Malay as the national language of Singapore. This plays a symbolic role as Malays are constitutionally recognised as the indigenous peoples of Singapore, and is also largely due to Singapore's geographical location in the Malay Archipelago.

In the early years, the lingua franca of the island was Bazaar Malay (Melayu Pasar), a creole of Malay and Chinese, the language of trade in the Malay Archipelago. English gained prominence during the British rule of Singapore as the language of government, law and business. Upon independence, English became the official medium of instruction across all levels of education in Singapore due to the country's heavy reliance on international trade, commerce and finance, thus displacing Malay as the common language. The three languages other than English were chosen to correspond with the major ethnic groups present in Singapore at the time: Mandarin Chinese had gained pre-eminent status with the overseas Chinese since the introduction of Chinese-medium schools; Malay was deemed the "most obvious choice" for the Malay community; and Tamil for the largest Indian ethnic group in Singapore. In 2009, more than 20 languages were identified as being spoken in Singapore, reflecting a rich linguistic diversity in the city. Singapore's historical roots as a trading settlement gave rise to an influx of foreign traders, and their languages were slowly embedded in Singapore's modern day linguistic repertoire.

Hokkien (Min Nan) briefly emerged as a lingua franca among the Chinese, but by the late 20th century it had been eclipsed by Mandarin. The Government emphasises Mandarin Chinese amongst Chinese Singaporeans, as the Government views Mandarin as lingua franca between the diverse non-Mandarin speaking groups which form the Chinese Singaporean community (derived historically from the various regions of Southern China), and as a tool for forging a common Chinese cultural identity within Singapore. Mainland China's economic rise in the 21st century has also encouraged a greater use of Mandarin, particularly Simplified Chinese. Other Chinese varieties such as Hokkien, Teochew, Hakka, Hainanese and Cantonese have been classified by the Government as "dialects"; governmental language policies on the use of “dialects”, such as the elimination of non-Mandarin Chinese ("Chinese dialects") usage in official settings, heavy restrictions of “dialect” use in television and radio media, the non-provision of non-Mandarin “dialects” language classes within the national education system, along with changing societal language attitudes based on perceived economic value, have led to language attrition and a sharp decrease in the number of speakers of these varieties of colloquial ancestral “dialects”, especially amongst the younger generations. In particular, Singapore has its own lect of Mandarin; Singaporean Mandarin, itself with two varieties, Standard and Colloquial or spoken. While Tamil is one of Singapore's official and the most spoken Indian language, other Indian languages are also frequently used by minorities.

Almost all Singaporeans are bilingual, as Singapore's bilingual language education policy mandates a dual-language learning system, with English being the main medium of instruction. Learning a second language has been compulsory in primary schools since 1960 and secondary schools since 1966; children are required to learn one of the three official languages as a second language, according to their official registered ethnic group (the associated language is classified as a “Mother Tongue” language). Since 1 January 2011, if a person is of more than one ethnicity and their race is registered in the hyphenated format, the race chosen will be the one that precedes the hyphen in their registered race. Within the national education system, students are also eligible to learn another approved third language, of their choice.

In modern Singapore, contemporary language issues frequently discussed involve the widespread and increasing language attrition of the second languages (ethnic Mother Tongue languages) amongst Singaporeans, due to the pervasive use of the English language in daily life within Singapore and its households.

Although Malay is de jure national language, Singapore English is regarded de facto as the main language in Singapore, and is officially the main language of instruction in all school subjects except for Mother Tongue lessons in Singapore's education system. It is also the common language of the administration and is promoted as an important language for international business. Spelling in Singapore largely follows British conventions, owing to the country's status as a former Crown Colony. English is the country's default lingua franca despite the fact that four languages have official status.

Under the British colonial government, English gained prestige as the language of administration, law and business in Singapore. As government administration increased, infrastructure and commerce developed, and access to education further catalysed the spread of English among Singaporeans.

When Singapore gained self-government in 1959 and independence in 1965, the local government decided to keep English as the main language to maximise economic benefits. Since English was rising as the global language for commerce, technology and science, promotion of its use in Singapore would expedite Singapore's development and integration into the global economy.