1865 - The College opened in September with 48 boarders and 25 dayboys. The architect was Mr. John Burke, the builders Messrs. Kelly of Granard and the total cost was £16,000. Fr. James Reynolds was the first President. Previously he had been Superior of St. Mel's Day School in the Market Sq.

1867 - Bishop Kilduff died of typhus fever, aged forty-seven, in the College he founded.

1871 - For most of the next decade the College was a major Seminary where students pursued courses in Philosophy and Theology right through to ordination. Approximately 650 former students of the College were ordained priests between 1865 and 2000.

1879 - The Theology class was discontinued and students for the priesthood went to Maynooth and Continental Colleges. The Intermediate Education Act came into operation, providing payment to Schools like St. Mel's on the basis of examination results.

1880 - The avenue of trees was planted during the presidency of Fr. Hoare who became bishop in 1895.

1884 - Student numbers dropped to 17 boarders and 19 dayboys. The fees were £30 a year for boarders and £4 for dayboys. Over the next ten years the College faced a tough battle for survival because of falling enrolments. Suggestions were made to invite a Religious Order to run the school or to turn it into a Training College for Primary teachers. Nothing came of these plans.

1896 - Bishop Hoare established a system of scholarships or half-burses which helped to increase the student numbers to 78 in 1897.

1908 - Irish was introduced on the Curriculum for the first time. Canon Fullam died aged forty-seven after fifteen years as President. Newspapers acclaimed the College's outstanding examination results, moving from 79th place in Ireland to 15th with the highest percentage of passes in the country in 1908.

1914 - Stained glass windows were installed in the College Chapel.

1915 - Golden Jubilee celebrations were marked with the opening of a new Gymnasium and Library (now the Study Hall), built at the cost of £3,000.

1921 - The College was raided by Crown Forces during the War of Independence. Student numbers stood at 135 and Canon Michael J. Masterson retired after thirteen years as President. General Sean MacEoin was feted at a banquet held in the college to mark his release from Mountjoy Jail.

1926 - The Intermediate Certificate and Leaving Certificate were introduced.

1928 - St. Mel's won the Leinster Senior Football Championships for the first time, beating Belcamp College in Croke Park by 2-1 to 0-0. In the next four years they lost three Leinster Finals. From 1933 to 1948 St. Mel's played in sixteen Leinster Senior finals and won fourteen of these.

1933 - New Dormitory and Baths were built.

1939 - The Emergency brought great hardship and food shortages. The President's diary at the time recorded that the College was allowed 18 pounds of tea per month for 143 people, half a pound of sugar and half a pound of butter per head per week and half a ton of anthracite per month for cooking.

1944 - Three Mercy nuns arrived to supervise the kitchen and the Infirmary. For the next thirty years nuns were to play an important role in the life of the school.

1948 - St. Mel's won its first All Ireland Senior Final, beating St. Patrick's College, Cavan in Croke Park By 4-7 to 3-3. The College again brought home the coveted Hogan Cup in 1962, 1963 and 1987.

1951 - St. Mary's was built at a cost of £12,000 to accommodate the Sisters of Mercy and other staff. There were 169 students enrolled, 120 of them boarders. Fees were £40 a year for boarders and £8 for day boys. The death took place of Monsignor Thomas Langan at the age of 98. He had entered St. Mel's in September 1865 and in 1935 his recollections of the early days of the College were published.

1954 - The St. Mel's P.P.U. was launched.

1965 - The Centenary year of the College's foundation was marked with the building of 'New Wing', providing accommodation for 100 boarders, as well as a new Refectory. 'Prefabs' were also built to cope with the increasing numbers.

1967 - Free Education was introduced. New lay teachers were appointed over the following years to cater for the influx of new students, mostly day boys.

1985 - A new Assembly Hall, Classrooms and Sports Hall were constructed.

1994 - St. Mel's won the Leinster title for the 28th time, beating St. Peter's, Wexford by   3-11 to 1-5.

1996 - There were 740 students and 42 teachers on the staff.

2000 - A new £2M extension was started and the Gymnasium was completed. The Junior team won the first Leinster title since 1975 while the Senior team were narrowly beaten in the Leinster Final by St. Patrick's College, Navan. The decision was taken to phase out boarding, with no First Year boarders being taken for the first time since 1865.