The May Fourth Movement was a Chinese anti-imperialist, cultural, and political movement which grew out of student protests in Beijing on May 4, 1919. Students gathered in front of Tiananmen (The Gate of Heavenly Peace) to protest the Chinese government's weak response to the Treaty of Versailles decision to allow Japan to retain territories in Shandong that had been surrendered to Germany after the Siege of Tsingtao in 1914. The demonstrations sparked nation-wide protests and spurred an upsurge in Chinese nationalism, a shift towards political mobilization away from cultural activities, and a move towards a populist base, away from traditional intellectual and political elites.

The May Fourth demonstrations marked a turning point in a broader anti-traditional New Culture Movement (1915–1921) that sought to replace traditional Confucian values and was itself a continuation of late Qing reforms. Yet even after 1919, these educated "new youths" still defined their role with a traditional model in which the educated elite took responsibility for both cultural and political affairs. They opposed traditional culture but looked abroad for cosmopolitan inspiration in the name of nationalism and were an overwhelmingly urban movement that espoused populism in an overwhelmingly rural country. Many political and social leaders of the next five decades emerged at this time, including those of the Chinese Communist Party.

Scholars rank the New Culture and May Fourth Movements as significant turning points, as David Wang said, "it was the turning point in China's search for literary modernity", along with the abolition of the civil service system in 1905 and the overthrow of the monarchy in 1911. The challenge to traditional Chinese values, however, was also met with strong opposition, especially from the Nationalist Party. From their perspective, the movement destroyed the positive elements of Chinese tradition and placed a heavy emphasis on direct political actions and radical attitudes, characteristics associated with the emerging Chinese Communist Party (CCP). On the other hand, the CCP, whose two founders, Li Dazhao and Chen Duxiu, were leaders of the movement, viewed it more favorably, although remaining suspicious of the early phase which emphasized the role of enlightened intellectuals, not revolution. In its broader sense, the May Fourth Movement led to the establishment of radical intellectuals who went on to mobilize peasants and workers into the CCP and gain the organizational strength that would solidify the success of the Chinese Communist Revolution.

During the May 4th Movement, the group of intellectuals with communist ideas grew steadily, such as Chen Tanqiu, Zhou Enlai, Chen Duxiu, and others, who gradually appreciated Marxism's power. This promoted the sinicization of Marxism and provided a basis for the birth of the CCP and socialism with Chinese characteristics.