Linguistic differences are much clearer than those of racial groupings. Two linguistic groups, the Indo-Aryan and the Dravidian, account for all but a tiny proportion of the population. Of the Indo-Aryan languages, Hindi, the official national language, is the most important. In its standard form and its many dialects, it is spoken by about 43 percent of the population and is understood by a large number of others. It is predominant in the northern and central regions. Included among the Hindi variations is Urdu, referred to until 1947 as Hindustani or Khari Boli, which is recognized as a separate "official" language in the Indian constitution. Urdu is also the official language of Pakistan and is spoken by most Indian Muslims (except in the far south and east).

Other important Indo-Aryan languages are Bengali (the official language of the state of West Bengal and also of Bangladesh), Panjabi (the official language of the state of Punjab and the most widely spoken language of Pakistan), and Marathi, Gujarati, Oriya, Assamese, and Kashmiri (respectively, the official languages of the states of Maharashtra, Gujarat, Orissa, Assam, and Jammu and Kashmir). Two other languages of the Indo-Aryan family are among the 15 regarded as official languages by the constitution: Sanskrit, a classical literary language, and Sindhi, spoken largely in the Sind province of Pakistan and also by Hindu refugees who came to India after partition in 1947. The list of official languages includes four Dravidian tongues: Telugu, Tamil, Malayalam, and Kannada, which predominate, respectively, in the southern states of Andhra Pradesh, Tamil Nadu, Kerala, and Karnataka.