The Cultural Revolution, formally known as the Great Proletarian Cultural Revolution, was a sociopolitical movement in the People's Republic of China (PRC) launched by Mao Zedong in 1966, and lasting until his death in 1976. Its stated goal was to preserve Chinese communism by purging remnants of capitalist and traditional elements from Chinese society. The Revolution marked the effective commanding return of Mao—who was still the Chairman of the Chinese Communist Party (CCP)—to the centre of power, after a period of self-abstention and ceding to less radical leadership in the aftermath of the Mao-led Great Leap Forward debacle and the Great Chinese Famine (1959–1961). The Revolution failed to achieve its main goals.

Launching the movement in May 1966 with the help of the Cultural Revolution Group, Mao charged that bourgeois elements had infiltrated the government and society with the aim of restoring capitalism. Mao called on young people to "bombard the headquarters", and proclaimed that "to rebel is justified". The youth responded by forming various Red Guards around the country. A selection of Mao's sayings were compiled into the Little Red Book, which became a sacred text for Mao's personality cult. They held "denunciation rallies" against revisionists regularly, and grabbed power from local governments and CCP branches, eventually establishing the revolutionary committees in 1967. The committees often split into rival factions and became involved in armed fights known as "violent struggles", to which the army had to be sent to restore order. Mao declared the Revolution over in 1969, but the Revolution's active phase would last until at least 1971, when Lin Biao, accused of a botched coup against Mao, fled and died in a plane crash. In 1972, the Gang of Four rose to power and the Cultural Revolution continued until Mao's death and the arrest of the Gang of Four in 1976.

The Cultural Revolution was characterized by violence and chaos. Death toll claims vary widely, with estimates of those perishing during the Revolution ranging from hundreds of thousands to millions. Beginning with the Red August of Beijing, massacres took place nationwide, including the Guangxi Massacre, in which massive cannibalism also occurred; the Inner Mongolia incident; the Guangdong Massacre; the Yunnan Massacres; and the Hunan Massacres. Red Guards destroyed historical relics and artifacts, as well as ransacking cultural and religious sites. The 1975 Banqiao Dam failure, one of the world's greatest technological catastrophes, also occurred during the Cultural Revolution. Meanwhile, tens of millions of people were persecuted: senior officials, most notably Chinese president Liu Shaoqi, along with Deng Xiaoping, Peng Dehuai, and He Long, were purged or exiled; millions were accused of being members of the Five Black Categories, suffering public humiliation, imprisonment, torture, hard labor, seizure of property, and sometimes execution or harassment into suicide; intellectuals were considered the "Stinking Old Ninth" and were widely persecuted—notable scholars and scientists such as Lao She, Fu Lei, Yao Tongbin, and Zhao Jiuzhang were killed or committed suicide. Schools and universities were closed with the college entrance exams cancelled. Over 10 million urban intellectual youths were sent to the countryside in the Down to the Countryside Movement.

In December 1978, Deng Xiaoping became the new paramount leader of China, replacing Hua Guofeng, and started the "Boluan Fanzheng" program which gradually dismantled the Maoist policies associated with the Cultural Revolution, and brought the country back to order. Deng, together with his allies, then began a new phase in China, by initiating the historic Reforms and Opening-Up program. In 1981, the CCP declared and acknowledged that the Cultural Revolution was wrong and was "responsible for the most severe setback and the heaviest losses suffered by the people, the country, and the party since the founding of the People's Republic." In contemporary China, differing views exist about the Cultural Revolution. Among some, it is referred to as the "ten years of chaos".