The Calcutta Boys' School is an independent private day school located in Kolkata (Calcutta), West Bengal. was founded by the Rev. James Mills Thoburn (Methodist Missionary to India, and later Missionary Bishop of the Methodist Episcopal Church), and was opened in 1877. It was endowed by Robert Laidlaw and others interested in the education of the sons of the Anglo-Indian and domiciled European community.

The origins of CBS are closely linked with the establishment of the Methodist Episcopal Church in India. In January 1873, the Reverend William Taylor founded the work of the Thoburn Methodist Episcopal Church in Calcutta (Kolkata). He was succeeded by the Reverend James Mills Thoburn. The latter's ardent preaching soon rendered the Entally Baptist Chapel unable to cope with the increasing number of converts. In February 1874, a new chapel was opened at 145 Dharmatala Street, built at a cost of 16,000 rupees largely due to the generosity of George Bowen of Bombay who donated 10,000 rupees. Soon even this chapel proved unable to accommodate the growing congregation, until a larger church was constructed on Dharamtolla Street, where it stands today. The New Thoburn Church was dedicated on 31 December 1875. In 1888 Rev. James Mills Thoburn was elected Missionary Bishop of India and Malaysia - the first ever Missionary Bishop in India.

Gilbert Samuel, who became Principal in 1997, furthered the cause of co-curricular activities, allowing the students of CBS to secure top positions at premier National and International contests regularly, including a second-place finish at the 2003 Biology Olympiad and the International Informatics Olympiad in 2004. In 2005 CBS won the under-16 national cricket tournament, and in 2004 the national rounds of the Inter School Frank Antony Memorial Debate.

The school offers courses in Science, Commerce and Humanities (started in 2019) for the students enrolling in ISC.

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• Official website