(September 1920-February 1922), unsuccessful attempt, organized by Mohandas Gandhi, to induce the British government of India to grant self-government, or swaraj, to India. It arose from the outcry over the massacre at Amritsar in April 1919, when the British killed about 400 Indians, and from later indignation at the government's alleged failure to take adequate action against those responsible. Gandhi strengthened the movement by supporting (on nonviolent terms) the contemporaneous Muslim campaign against the dismemberment of Turkey after World War I.

The movement was to be nonviolent and to consist of the resignations of titles; the boycott of government educational institutions, the lawcourts, government service, foreign goods, and elections; and the eventual refusal to pay taxes. Noncooperation was agreed to by the Indian National Congress at Calcutta in September 1920 and launched that December. In 1921 the government, confronted with a united Indian front for the first time, was visibly shaken, but a revolt by the Muslim Moplahs of Kerala (southwestern India) in August 1921 and a number of violent outbreaks alarmed moderate opinion. After an angry mob murdered police officers at Chauri Chaura (February 1922), Gandhi himself called off the movement; the next month he was arrested without incident. The movement marks the transition of Indian nationalism from a middle-class to a mass basis.