St. Marys College is an all girls Catholic-maintained secondary school and Specialist Science School located in Derry, Northern Ireland. Situated in the heart of the Creggan area of Derry, it attracts pupils from a wide catchment area, with an enrolment of nearly one thousand pupils aged 11–18 and a staff of 92. It opened in 1959.
It was announced in early around 2001 onwards that St. Marys and St Cecilia's College would compete for a new school in the grounds of the former Templemore Secondary school on the Northland Road. St. Marys got the grounds but St Cecilia's College is currently located in the old Templemore School while their new school is being rebuilt on Blighs Lane. Although it was first thought that the new school would be ready for 2007, this date has been changed to 2009.
The school is in a strongly republican area but is noted for establishing cross-community links. The school has achieved much success throughout the world. It was the first school in the UK to receive three charter marks for excellence, the government's public service "gold medal". Dame Geraldine Keegan had been Principal of the school for many years but in 2006 Mrs Marie Lindsay a Science Teacher in the school became the new Principal. Notable alumnae include Bronagh Gallagher.