In 1963, the Brothers of St Patrick opened the school in Delhi at the invitation of the Army. It started with four Brothers, six teachers and 85 students. The first Principal was Bro. E.T Dunne who was in charge of the school till January 1969. The foundation stone was laid on 6 January 1963, by General Bhagwati Singh, who was at that time G.O.C of Delhi Area, New Delhi. The school was first housed in eight tents - 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 1963. This building was however not complete as the number of students were increasing and a Science Block was required. The staff and students organised fetes in 1966 and 1968, which brought in enough money to help complete the building.
Facilities
The school is widely regarded to be one of the best schools in New Delhi in terms of infrastructure, sports facilities, etc. In addition to two computer labs, two libraries, and three science labs, the school also has numerous sports fields/courts - onesynthetic tennis courts, one soccer fields, a cricket ground, volleyball court, one outdoor badminton courts and onesynthetic basketball court. In addition to these, there is a science park, skating rink, swimming pool and centrally air-conditioned auditorium with a capacity of nearly one thousand people. There are many study circles and clubs for a variety of activities, namely debates, elocution and quiz, dramatics, music, choreography, and photography. Additionally, the school is host to a large number of inter-school events, most notable being Bro. Aloysius Recitation Competition, Bro Bergin's Music Meet, Bro. Mahony football tournament, and the Matrix-Ecomm Buzz Symposium.
In its 50-year history, Mount St. Mary's School has won numerous accolades across sports, co-curriculars and academics. The Ecom-Buzz and Matrix Symposium, a series of inter-school competitions, organized solely by the students has been the recipient of media praise. Students have won an edition of the national level Bournvita Quiz Contest. In 2012, they came fifth nationwide in the Wild Wisdom Quiz, organized by the World Wide Fund for Nature.
Notable alumni
Arnab Goswami Former Editor-in-Chief, Times Now News Channel
Gaurav Kapur TV and Radio Host and Actor
Hitesh Madan Founder and lead guitarist of music band Eka and Euphoria
Jaspreet Jasz Singer
KK Playback Singer
Manan Sharma Cricketer - India U-19 and Delhi State
Raghav Sachar Singer-songwriter, Music composer, Instrumentalist
Shaleen Malhotra Actor
Vinod Khosla Co-founder of Sun Microsystems, Venture capitalist - Khosla Ventures