Ch'ing-k'un Yang (Chinese: 楊慶堃; pinyin: Yáng Qìngkūn; 1911 – 10 January 1999), better known as C. K. Yang, was an American sociologist who pioneered the application of sociological theory to the study of China. He was known for his contributions to the study of Chinese religion and his argument that religion in China was "diffuse" and present in many aspects rather than being institutionalized in churches. In 2007, friends and colleagues published a festschrift in his memory, Social Change in Contemporary China: C. K. Yang and the Concept of Institutional Diffusion.