In the course of China’s history, the term datong (great unity) has been interpreted in multiple ways. In this lecture, the concept as understood in the Liji will be discussed, after which focus will be on the way in which the perceived loss of the ‘great unity’ within ‘all-under-heaven’ (tianxia) at the end of the Qing dynasty (1644–1911) and the endeavor to reconstruct the empire as a modern nation-state starting in the early twentieth century, informed the way the term datong was interpreted. Special attention will go to Kang Youwei’s (1858–1927), Liang Qichao’s (1873–1929), Sun Zhongshan’s (1866–1925) and Mao Zedong’s (1893–1976) interpretations of the concept. The lecture will conclude with a discussion on the contemporary New Confucian interpretation of the concept datong.