During the two-thousand year history of Buddhism in China, Guanyin has remained as the most famous Buddhist deity. A Chinese saying aptly describes the great popularity of this savior bodhisattva, “Everybody knows how to chant A-mi-tuo-fo, and every household worships Guanyin.” This talk will discuss how and why this came to pass. What are the scriptural bases of the cult, the rituals and practices which promote the belief, and the legends and visual culture which contribute its spread? More intriguingly, why did Guanyin become a “Goddess of Mercy”, a nickname coined by Jesuit missionaries, in late imperial China? The cult of Guanyin can serve as a case study of the mutual interaction between Buddhism and Chinese culture.