Hindi Diwas or the National Hindi Day is celebrated every year in India on September 14 in order to mark the adoption of Hindi as the official language by the Constituent Assembly of India on September 14, 1949.

• The decision of using Hindi as an official language of India was legalised by the Constitution of India on January 26, 1950.
• India's first prime minister Jawaharlal Nehru decided to celebrate Hindi Diwas on this day.