The three-language formula is a language learning policy formulated by the Indian government in 1968. It aims to promote multilingualism and national harmony. The policy prescribes studying three languages - the regional language or mother tongue as the first language, Hindi or English as the second language, and English or another modern Indian language as the third. While the policy aims to enhance cognitive development and career opportunities, there have been issues in implementation due to lack of resources and reluctance of some states to adopt Hindi. The Indian constitution contains various provisions regarding the official use of languages and promoting linguistic diversity.