This chapter introduces and examines the philosophy of Dongsun 張東蓀 (1886–1973). From the 1920s to the 1940s, Zhang Dongsun was one of the most important philosophers in China. Part of his influence was due to his excellent work in introducing Western philosophy to China. However, Zhang’s significance in modern Chinese philosophy is mainly due to his role as the first one to establish an epistemology-centered philosophical system. Zhang’s theory of knowledge began with a pluralistic epistemology and culminated in a cultural epistemology. Western theories of knowledge, especially Kant’s epistemology, provided a foundation for his epistemological pluralism. The Buddhist view of the universe greatly inspired his cosmology—panstructuralism. However, Zhang based his philosophy more on assimilating and synthesizing work in Western philosophy than on reforming traditional Chinese philosophy. His cultural epistemology sought to explore the social and cultural nature of knowledge, which is of greatest interest today. To illustrate and demonstrate his cultural epistemology, Zhang also undertook comparative studies of Chinese and Western philosophy. Especially insightful are his investigations of how differences in language influence differences in philosophy and how cultural differences determine differences in logical thinking. Zhang’s comparative studies remain of great value in our time.