Sporadic extensions have occurred, including during the early 1930s and the late 1970s – science laboratories and a demonstration room were added in between these two periods of major building work.

Sportsmen educated there include Olympic athletes, Mark English (a middle-distance runner) and Philip Deignan (a cyclist who later turned professional), as well as several current county footballers, among whom are Michael Murphy, Shaun Patton and Niall O'Donnell.

Other staff members (past and present) include Ollie Horgan, Gary McDaid, Charlie McGeever and John Wilson, who later served as Tánaiste.

[4] Then, in the following century, Bishop Patrick McGettigan appointed a priest as a teacher of Greek, Latin and mathematics at a building on Castle Street in 1825.

[5] As scholar numbers began to outgrow the facilities available at the Literary Institute, Bishop of Raphoe Patrick O'Donnell sought to establish a boarding school to provide a classical education.

[1] Diocesan colleges experienced an increasingly favoured stature at the time and were set up to give an unrivalled Catholic education to boys of every class.

[13] A classical scholar, he taught Latin and Greek, served as dean and as bursar and involved himself in the college's annual opera; he had a special fondness for the operettas of Gilbert and Sullivan.

[17] After completing a doctorate and spending some time working at Knockbeg College, he joined the St Eunan's staff in 1942 as a teacher of science and mathematics.

[17] Peter McMahon, eighth president of the college, had, like his predecessor, been educated there and joined the staff in 1953, holding the posts of Dean and Bursar (just as McLoone had before him).

Appointed to the presidency in 1971, he steered the college through the difficult years that followed the introduction of "free education" by Donogh O'Malley, who made the decision without consulting his colleagues in cabinet.

With a growing population of children to be accommodated, the curriculum overhauled, and classical subjects demoted to suit the needs of the less able, the less academic child introduced to the realities of an advanced secondary education, an extension to the college was required by the mid-1970s.

Carney served as president of the college until 2009, taking up residency as priest at Ramelton where he was in situ when local scientist William Cecil Campbell won the 2015 Nobel Prize in Physiology or Medicine.

[36] A banquet was held that evening, at which a toast was proposed to the Bishop of Raphoe, William MacNeely and the hope expressed that he would be alive to witness the Golden Jubilee (he was).

In April that year, Patrick Kerr, College President throughout the 1930s and the first half of the 1940s, and who had since risen to the rank of Archdeacon of the Roman Catholic Diocese of Raphoe, died.

[37] As with the earlier jubilee, High Mass was held in the nearby cathedral, this time presided over by a former member of staff, John McMackin (who had by then become a professor of English at the pontifical university of St Patrick's College, Maynooth).

[37] Among the other guests were Bishop of Derry Neil Farren and two former students – the then Leas-Cheann Comhairle Cormac Breslin and Minister for Local Government Pa O'Donnell.

[13][37] He was promptly returned to Killybegs that same evening and interred that Friday following a requiem mass which was overseen by Bishop MacNeely and each priest of that diocese.

[36] It opened in September 1933, when it was used initially as accommodation for those priests who had, until that time, lived at addresses on the adjacent College Row, close by the school gates.

Transition Year modules offered – past and present – include first aid, tennis, cookery (introductory demonstrations for the boys provided by the dinner ladies in the college kitchens) the study of drama and performance (held at An Grianán Theatre), electronics (using the facilities of a local third-level institution) and driver awareness (an introduction to the rules of the road for prospective drivers) and a referee course (for those interested in football).

[74] In 1979, a college team managed by Paddy Tunney and featuring repeat Leaving Certificate student Charlie Mulgrew won a MacLarnon Cup against De La Salle by a scoreline of 0–11 to 0–7.

[76] Gordon continues to manage the college's Gaelic football team as of 2018, when he led them to a narrow one-point loss after extra-time in an Ulster final replay.

That campaign went as follows: On 25 March 2007, the college defeated Rathmore by a scoreline of 1–9 to 2–3 at Casement Park in Belfast (they had travelled there six days earlier only for the match to be postponed).

[80] During the twentieth century, three students played senior inter-county football while attending the college; these were Seamus Hoare, Martin Carney and Paul McGettigan.

[87] The relative lack of success of the college – and hence Donegal, as it is the county's foremost competitor – in the MacRory Cup has been explained by Declan Bonner as follows: "The main reason... is because some of the big schools in the north take in a huge amount of students, and can boast players from up to ten to twelve clubs sometimes.

[90] The first success at national level was the defeat of Saint Joseph's, Fairview, by 1–0 in the final of the 1978 FAIS Junior Cup held at Tolka Park.

The first performance held there was of Finnola or The Borrowed Bride, a piece penned by a Loreto sister especially for the Aonach of 1906 (a final fundraising event at the newly opened College).

[103] They previously took place on an enlarged stage in the Study Hall, with the public admitted — thus allowing for expenses on costumes and performing rights to be covered.

Efforts were made during the 1980s and 1990s to revive these performances, albeit with the newer musical theatre in place of the opera/operettas of old – the college even sanctioned a production dating from as recently as the early 1970s.

Participants in the "Computer Club" of the 1980s included Neil Gordon (who would later teach at the college, organise annual ski trips abroad and manage the football team) and Kevin Gillespie (later Monsignor and Cathedral Parish Administrator).

[27] The 2008 trip, when Neil Gordon led a troupe of skiers to the United States, proved eventful – the Airbus craft bringing them home experienced motor difficulties in mid-flight and had to return to Logan International Airport after several hours in the air.