The School is affiliated to the C B S E Delhi and thus, in the matters of Admission, Examination, Scheme of Studies, Attendance and other relevant matters the School ensures very strict adherence to C B S E Curriculum, Bye Laws, and Guidelines. Under Subjects of Studies, till X, the School offers three languages, viz, English, Hindi and Sanskrit (till VIII). The learning areas also include Mathematics, Science, Social Science, Work Education, Art Education and Physical Education. The School has made Moral Science a compulsory subject for all to instill in students moral values and to develop National Identity.
At Higher Secondary Level the School offers English Core, Hindi Core, Mathematics, Physics, Chemistry, Biology, Accountancy, Business Studies, Economics, Computer Science (C++), General Studies, Work Experience and Physical and Health Education. These subjects are offered in groups and, presently the Institution offers the following Groups:
• English Core, Physics, Chemistry, Biology & Mathematics
• English Core, Physics, Chemistry, Biology & Hindi
• English Core, Physics, Chemistry, Biology & Computer Science
• English Core, Physics, Chemistry, Mathematics & Hindi
• English Core, Physics, Chemistry, Mathematics & Computer Science
• English Core, Accountancy, Business Studies, Economics & Mathematics
• English Core, Accountancy, Business Studies, Economics & Hindi
• English Core, Accountancy, Business Studies, Economics & Computer Science
General Studies, Work Experience & Physical and Health Education are compulsory for all despite the choice of their group. At the time of registration for admission to Class XI, the students can show their choice of groups in the order of preference. However, the groups will be allotted purely on the basis of MERIT, ie the Grade obtained in the AISSE. Under normal condition, all who have been students of St. Mary's in X Class and have secured a passing grade (above 'E') are eligible to be admitted to XI Class. However, if the Principal feels, admitting a student could be detrimental to the Institution and the fellow students his/her admission will be summarily rejected. The School has around 150 seats under Science Stream and about 50 under Commerce. Normally, everyone interested in getting admission manages to get a seat but, the possibility of getting the group of their preference depends on their performance in X. The changes brought in by the C B S E, from time to time, in Curriculum and other related matters are/will be implemented with immediate effect.