In 1905 three Mercy sisters arrived in Castleblayney by train with the intention of setting up a school in the town. They had come in response to a request from the people of Castleblayney, who had no educational opportunities for girls at that time. The local people offered to provide accommodation which is presently the house inhabited by the sisters. The original convent was built on a site which had previously housed a brewery.

The Sisters began the Primary School in 1912 and in 1918 Scoil Mhuire Secondary School was opened in the Art Room building, which consisted of 2 rooms with a partition.

In 1962 the original two storey building was opened and the school began to offer facilities for girls who wished to board. The upstairs of the main building housed the dormitories. The school continued to offer boarding facilities up until 1974.

In 1971 Our Lady’s Secondary School came into being through the amalgamation of Scoil Mhuire and the Boys Secondary School, St Mary’s. The President of St Mary’s, Fr Frank McKenna , and staff John Gallen, Frank McQuaid and Sean Glynn all transferred to Our Lady’s and Fr McKenna became the first Principal of the new school, a position he held until 1974. Mr Gerry Gillanders (after whom our Student of the Year Award is named) was Vice-Principal.

In 1974 Sr. Margaret Lyons became Principal. In 1975 the lower pre-fabs were built. (In 2000 they were finally demolished to allow for a new car park). The original All Weather Pitch was also built at this time, which meant that some of the sisters who were interred there had to be exhumed and re-interred in the present Convent graveyard.

In 1979 the Gym was opened and in 1980 the GPA and surrounding classrooms were built. Both of these events were highly significant at the time and much effort, thought and rehearsal went in to the opening of these facilities.

In 1987 Mr John Gallen was appointed Principal.

The 27th November 1992 saw the opening of the Concert Hall by the then Uachtarán na hEireann Mary Robinson. In 1994 the new tennis courts were opened and two years later new pre-fabs (beside the Concert Hall) were built.

At this stage plans were well underway for the building of a new extension on account of the ever increasing numbers attending Our Lady’s. This extension was completed and opened for use in September 1999 and the official opening by the Minister for Education of the time, Dr Michael Woods took place in May 2000.

The original school building – the Old Hall – now the Art Room, was given a new lease of life with a complete restoration which is indicative of its importance as an item of heritage, not only for the school, but for the whole town of Castleblayney.

In 2002 Mr Gerard McGuill was appointed Principal.

In 2003 an in-house chaplaincy service was introduced whilst in the summer of 2005 the roof of the GPA was completely replaced. October of the same year saw the All-weather pitch replaced with a floodlit Field Turf pitch, adding further to the excellent facilities at Our Lady’s. This new venture was viewed by President Mary McAleese when she visited the school in December 2005.

In 2014 Mr Eddie Kelly was appointed Principal. Mr Kelly, a native of Castleblayney, is the first past pupil to hold this position.

In 2015 all the windows and doors in the Old two storey building were replaced and new flooring was also installed in this area.

In 2015 student enrolment passed 700 for the first time.

There have been many outstanding achievements in the history of Our Lady’s Secondary School, achievements too numerous to mention, in addition to successes and accomplishments of diverse natures which make them difficult to categorise. However, there are a number achievements that are particularly deserving of note in this short synopsis of our history., The first is the success of pupil Mary Kelly in winning the National Young Scientist of the Year Award in 1976. Mary subsequently went on to win the European Title. In 2015 Christopher Carragher emulated Mary’s success by winning the National Sci-Fest Competition going on to represent Our Lady’s and Ireland at the Intel World Science Fair in the United States where he was presented with an award recognising his innovative achievements.

Our Lady’s Secondary School has long been to the forefront of Culture, Drama and Music producing a first class biannual musical since the 1980s. The School Choir won the Walton’s Music for Schools National Title in 2016 and has represented Ireland at the Llangollen International Music Festival in Wales on a number of occasions bringing home World Titles in 2010 and 2016.

Another outstanding achievement came in 1993 when our Senior Boys Basketball team captured the All Ireland title and as a result went on to represent their school and country in Athens, Greece. Then in 2005 the Senior Boys Gaelic Football team were crowned Ulster and All Ireland Champions after a tremendous year. The Senior Girls GAA Teams won the Ulster C Championship in 2012 & the Ulster B in 2013 and again in 2016. The Senior Girls Basketball Team won the All Ireland B Championship in 2013.In 2015 Our Lady’s captured the Mac Larnon Cup for a second time. In 2016 the U16 Girls and Senior Girls Teams won Ulster Championships. Over the years students have been awarded a large number of national (McManus and Naughton), university and college scholarships while a significant number of sporting successes and individual All-Star Awards have been achieved.

Our Lady’s Secondary School has experienced many high points since its inception in 1971. It has consistently been at the forefront of educational change. This is particularly true in the case of Special Needs Provision and also in the way Our Lady’s embraced ICT at a very early stage and continues to lead innovation and change in this area. These successes would not have been possible without the commitment and dedication of the many exceptional teachers who have graced the corridors of our school and the energy, enthusiasm and efforts of generations of exceptional young people.