1962 The school started as a single stream Day school with funding from Sisters of mercy and the Kenyan government. Inititially it occupied buildings of the older Primary school section of Our Lady of Mercy Primary School, with both sections under one Head-teacher.
1965 First 18 candidates sat for Cambridge Certificate of Education
1966 The school became a girl's only school therefore a separate entity from the primary school with its own Head-Teacher.
1974 The school became a government maintained secondary school giving grants-in-aid for recurrent expenses as well as paying Teachers' salaries.
The government gave grants for the construction of a science laboratory while a German funding agency gave funds for Home-science unit
1980s Negotiations with Nairobi City Council began towards getting one of the plots earmarked for primary school in the Nairobi South B development plan in order to expand and admit more students in both schools.
1980s Parents Teachers Association was set up.
1985 Current School Plot was allocated to Catholic Archdiocese of Nairobi.
1987 8th July- His Excellency Daniel Arap Moi presided a Fund-raising harambee held in the primary school grounds.
In the month of September, construction of the first phase of the current school began with help of the funds.
1989 The school became a double stream secondary school.
13th April- the school moved to its current site from the facilities it occupied for 27 Years in the same building as Our Lady of Mercy Primary school-Nairobi South.
1992 A second science laboratory, library and classroom were built with the help of parents.
1997 Construction of the school hall and Kitchen began and was built using funds from parents, school walks, dinner dance and school luncheon.
2001/2002 School's perimeter wall was Constructed.
2005 School bus was Purchased by Parents.
St. Margaret's Chapel was built by Fr. George Smyth and Our Queen of Peace Catholic Parish in Honor of his Mother- Mrs. Margaret Symth.
2008 The school became a triple stream secondary School with the help of The ministry of education's Constituency Development Fund and Parents
2010 A further three classrooms were built with the help aid of parents.
2011 Basketball Court was built by Fr. John Slinger and Our Lady Queen of Peace Catholic Parish- Nairobi South.
2012 The school celebrated a 50 year Golden Jubilee for its existence and service to the community.
2015 The school became a full boarding Girl school with construction of the dormitory still on-going.
2015 To date. In August the school Receives a new principal, Mrs. Kiruja Jayne, the Former school's Deputy Principal.