The Mary Erskine School comprises approximately 760 girls aged 12-18. Founded in 1694 by Mary Erskine and the Royal Company of Merchants of the City of Edinburgh to educate and care for the daughters of city burgesses who found themselves in reduced circumstances, it is the oldest girls’ school in Scotland and one of the oldest in the whole of the United Kingdom. Since 1989 the Royal Company of Merchants of the City of Edinburgh, has delegated powers to the Erskine Stewart's Melville Schools’ Governing Council.

Since 1978 the school has been twinned with Stewart's Melville College. Through this arrangement, the senior schools are separate and single-sex but are each led by the Principal, while all the girls and boys below the age of 12 are educated together in the ESMS Junior School.  Senior school boys and girls come together in orchestras, choirs, drama and musicals, as well as in numerous Outdoor Learning projects and in the Combined Cadet Force. Since August 1999, the Sixth Year has become a genuinely 'twinned' experience, with boys and girls jointly comprising a single academic, pastoral and social unit.

The Erskine Stewart's Melville Schools have a charitable foundation and today provide financial assistance to over 150 bursary holders, who attend Stewart's Melville College or The Mary Erskine School.

The school, named The Mary Erskine School in 1944 to mark the 250th anniversary of its foundation, has been housed on various sites in the city - the Cowgate, Bristo, Lauriston and Queen Street. In October 1966 the school moved to purpose-built accommodation on the magnificent 38 acre site adjoining Ravelston House. Facilities include a Sixth Form Centre, Sports Hall, floodlit Astroturf hockey pitches and tennis courts. The Sports Centre houses the National Cricket Academy and the Scottish Cricket Offices. A community sports facility is in operation seven days a week, outwith school hours and the project, which is linked to the sports facilities at Queensferry Road, are managed by the Community Sports Development Manager.

The Erskine Stewart's Melville Schools have a charitable foundation and today provide financial assistance to over 150 bursary holders, who attend Stewart's Melville College or The Mary Erskine School.