It is the only denominational secondary school for Dumbarton, the nearby Vale of Leven Community and Helensburgh.

In 1990 the two were merged into a new school, using the newer buildings of Notre Dame in the Castlehill neighbourhood on the west side of Dumbarton (completed in 1969).

The school colours, green and blue were chosen from the existing schools[3] and are the colours most commonly associated with the namesake religious figures; blue for the Virgin Mary and green for St. Patrick.

[4] The school serves the catchment of Dumbarton, Alexandria, Balloch, Helensburgh and the Rosneath peninsula.

Our Lady and St Patrick's is a major part of the Catholic community for its relatively large catchment area and regularly performs a celebration of mass for events such as local Primary 7 graduation into the school and for Remembrance Day commemorations.