The Oriental Seminary started in 1829 by the educator Gour Mohan Addy, was the earliest privately run, first-rate school for children of Hindu parents in Kolkata (then known as Calcutta). It was open only to boys of Hindu parents. It was possibly India’s first fully private school, as even Hindu School, then known as Hindu College,and also Hare school had to abide by certain government guidelines. In earlier days, students wanting to study English had to go to the missionary schools, where they were subject to substantial religious influence. The establishment of a school for learning English, free from religious influences was a major contribution of Addy. Traditional Indian education centres which taught Sanskrit and/or Persian had started fading out.
The school was first located at Benshohata. Thereafter, it shifted its location thrice before moving into the present building on Rabindra Sarani (earlier known as Chitpur Road) in Jorasanko, often wrongly referred to as Chitpur. It was inaugurated by the governor of Bengal, Lord Carmichael, in 1914. Its monthly fee of Rs 3 compared to Hindu School's Rs. 5 helped it to draw more students.
In 1836, a morning session for the infants was started. Bengali was introduced as a medium of instruction in 1839. By popular demand, three branches of the institution were set up in Chitpur, Bhowanipur and Belghoria. The school opened a girls' section in 1934. The higher secondary section of the school became co-educational in 1991. The building, constructed by Martin Burn, was declared a heritage structure in 1999.
The first president of Indian National Congress, barrister W.C.Bonnerjee was an ex-student and the first president of the governing body of the school till his death in 1906. He was succeeded by Sir Ashutosh Mukherjee who was associated with the school as the president of its governing body from 1907 to 1922. Annie Besant was the president of the annual function of the school in 1926.
Gour Mohan Addy (January 20, 1805 – March 3, 1846) started the school without any support from the government. For the junior classes, he appointed Eurasians, in the intermediate classes he had Bengali teachers and for the upper classes he appointed highly qualified Englishmen or Bengalis. He died in a boat accident in the Hooghly river, when returning from Serampore, after searching for a teacher for his school.