St. Mary's School, Mumbai or St. Mary's School I.C.S.E, is a private Catholic secondary school for boys located in Mazagaon, Mumbai, in the state of Maharashtra, India. Founded by the Jesuits in 1864, the school is affiliated with the Indian Certificate of Secondary Education (ICSE). The school is amongst the oldest, continually running, private schools in India. It is also ranked amongst the top day schools in the country.