In 1963, the Brothers of St Patrick(Patrician Brothers) opened a new school call Mount St. Mary's in the capital of India on the invitation of the Army. It started with four brothers, six teachers and eighty - five students. The first principal was Bro. E.J Dunne and he was in charge of the school till January '69. The foundation stone was laid on the 6th of January 1963, by Genral Bhagwati Singh, who was at that time G.O.C of Delhi Area,New Delhi.
The school was first housed in eight tents(with seven classes)- there were only two students in the seventh standard. The building work started immediately, and the entire school moved into the building in July 1963. Two Floors were completed in December '63.This building was however not complete as the number of students were increasing and a Science Block was required. The staff and students put a joint effort in two very successful fetes, in 1966 and 1968, which brought in a considerable amount of money to help complete the building now standing very impressive, in a symphony of red and cream with expansive grounds and beautiful gardens