It is a Christian school run by the Protestant Church of North India and its primary language of instruction is English.

Although previously a college, the school was stripped of its college status by the British Government when freedom-fighter Bina Das, a student of the school, attempted to assassinate the Governor of Bengal, Stanley Jackson, in the Convocation Hall of the University of Calcutta on 6 February 1932.

From 1908 to 1931, St. John's Diocesan School remained the only Christian women's college of good repute in eastern India.

Hoare wrote in a letters to her brother in England: "...my idea of the future of our Diocesan School is that it should be an institution not confined to any particular society or an elite group..." She died at age 48 in 1892.

The school teaches from the Preschool level to the higher secondary (10 + 2) and is affiliated under the WBBSE and WBCHSE.

Inside the campus there is a park, three play grounds, a basketball court and seven buildings in a lush green surrounding.

The school has an LCD projector in the library for audio-visual aid to teaching as well as for showing films to the junior students.

The school library called ‘Dio Bibliothique’ has a seating capacity of 200 students and has a collection of over 35,000 books and subscribes to periodicals and dailies.

Piano, organ, keyboard, Octapad, guitar and drums are the instruments which are taught in the school.

A tradition since 1990 has been donation of one onion and one potato on every Friday by each student from Lower Nursery to Class XII to the school which goes to the St. Joseph's old age home run by the Little Sisters of the Poor.

Some of the reflections of the school's devotion for the welfare of the public at large include the 2004 Tsunami relief, 2009 Aila relief programme, 2008 drinking water supply programme, slum rehabilitation activities, educational Tours for underprivileged children, and a free Seva Clinic at St Mary's Church, Kolkata.