The school was founded in 1980 and was named after Monsignor James Sheahan, a Catholic priest who served in Orange for nearly 50 years. The school was formed by the merger of Santa Maria College, a girls' school, and De La Salle College, a boys' school..
Design
The first stage of James Sheahan Catholic High School was completed in late 1977, when secondary school boys from the local De La Salle College began to attend. In 1980 the school became co-educational when girls from Santa Maria School began attending. The original design only consisted of a 2-3 floored C-shaped building housing classrooms facing North with a wing leading off the edge of the East housing the office and a four-room building adjacent to the corner of the West edge which housed the first science labs. There was also a large house which was where the De La Salle Brothers lived for several years. There were also four basketball courts, four netball courts and two cricket nets down from the school on a large asphalt expanse known as "the tarmac". Several years later another two-floored C-shaped extension was added containing more classrooms and several art rooms closing off the original C-shape creating the Quad later on one side of the quad was turned into a large staff room. There was a single storey industrial technology wing on the edge of the second C. Several demountables were located on the exterior side of the second C. In 1987, a Chapel was built in the school grounds which still stands today. There are also six tennis courts, situated between the netball courts and the now-relocated demountables. In 1994, a two-storey wing was added to the north-west side of the main building, extending beyond the Chapel and creating the western boundary of what is now known as the "Senior Area". The demountables were also removed and now serve as storage sheds adjacent to the tennis courts. A large, separate two-storey building was constructed on the West side of the Quad to house the new library and food technology rooms. To the south of that building, the original four-lab science block stands, including the renovated staffroom. Slightly further south, the newer, two lab science block stands, bounded by the staff carpark, the old labs, the tarmac and adjacent houses. Behind the library and food technology rooms is a large Industrial Technology building, which houses woodwork, metal work, mechanics, sewing, graphic technology and computing rooms. There is also a staff room. In 2001, a large multipurpose hall was built. The hall provides two indoor basketball courts, a P.E. staffroom, P.E. storerooms, a large gym mezzanine a drama/dance room, music room and changing rooms with toilet amenities. This coincided with the construction of an oval with 2 football fields and a cricket pitch, which is named Norton Park. The school hall was officially named Mercy Hall in 2011. In early 2016, the construction of a large facility began with an outdoor amphitheatre, music rooms and a large multipurpose room. The original date of completion was 30 September, 2016. The project was completed in May 2017, with the official opening taking place that same month with distinguished guests.
