The Church of South India is an autonomous Protestant church of South India. It was inaugurated in September 1947, and formed from the union of Anglican, Methodist, Congregationalist, Presbyterian, and Reformed churches. Discussion of merging South India's main Protestant denominations began at a 1919 conference at Tranquebar (Tarangambadi), and the process was completed shortly after India's Independence.

The church is organized into 21 dioceses, each under the supervision of a bishop, including one diocese in Jaffna, Sri Lanka. The Church as a whole is governed by a Synod, which every two years elects a presiding bishop, called a moderator, who serves as head of the church. The Church has 3.8 million members in 14,000 congregations. The great majority of members are in the Indian states of Andhra Pradesh, Karnataka, Kerala, and Tamil Nadu, but also in Sri Lanka, the United States, the United Kingdom, Australia, Canada, Bahrain, Kuwait, and the United Arab Emirates.

The church has its own service book and communion service, elements of which are drawn from the different denominations that made up the church. It is in limited communion with the Anglican Church and the Episcopal Church of the United States.

Dioceses: Coimbatore, Dornakal, East Kerala, Jaffna, Kanyakumari, Karimnagar, Karnataka Central, Karnataka North, Karnataka South, Krishna-Godavari, Madhya Kerala, Chennai (Madras), Madurai, Medak, Nandyal, North Kerala, Rayalaseema, South Kerala, Triuchirapalli-Thanjavur, Tirunelveli, and Vellore.