Subjects taught included English, Latin, modern languages, mathematics, singing, elocution, physical culture, freehand and geometrical drawing, painting, music, needlework, and woodcarving.

Within the first two years the school was extended along Villiers Street, and three students sat for and passed the Civil Service Entrance Examination.

OLMC was one of the first schools in New South Wales to be registered for the Tate Langdon Act in 1913, which introduced the more competitive exam orientated approach to education of the Intermediate and Leaving Certificate years.

In 1922, Dorrie Murphy convinced Mother Francis Kearney to support the foundation of an Ex-Students' Association.

This was a direct result of the incorporation of the college and the appointment of a board of directors in 2002 by the trustees of the Sisters of Mercy Parramatta.

By 1929, the expansion of the school led to the erection of a new building in order to accommodate the 150 borders and 200 day pupils.

The building provides facilities in science, food technology and hospitality, and a library, senior study and canteen.