The introduction to the book Indigenous Churches: Christian Affiliations and Inter-denominational Relationships in Lowland South America situates the book’s topic and discussions within the wider frameworks of lowland South American ethnography and anthropological research on Christianity. It first parses previous studies of Christianity in South American lowlands, concentrating on the Amazonian and Gran Chaco regions, and then moves on to present the book’s contribution to the discussions on Indigenous churches and inter-denominationalism in the field of Anthropology of Christianity. Finally, it examines the topics the book’s chapters collectively show to be central for understanding the notion of “Indigenous church” anthropologically in lowland South America.