This chapter explores the Syriac chant traditions among the group of South Indian churches, collectively referred to here as the “St. Thomas Christians.” These churches, which encompass a variety of denominational communities in Kerala, trace their origins to the apostolic and Chaldean/East Syriac sources of West Asian Christianity, later articulating also with the Antiochene liturgy and Orthodox Christianity in the late seventeenth and eighteenth centuries. They have defended their linkages with the Syriac liturgical and musical traditions against the incursions of foreign Catholic and Anglican missionaries, and later a wider variety of Catholic and Protestant movements within India. The chapter suggests that they accomplished this, in part, by only selectively accepting musical, liturgical, and theological elements that arrived with each of these missions. But more recently they have accomplished this by retaining Syriac chant melodies even as churches began to sing in vernacular languages such as Malayalam.