O’Nolan attends Blackrock College where he is taught English by President of the College, and future Archbishop, John Charles McQuaid. He also spends part of his schooling years in Synge Street Christian Brothers School. His novel The Hard Life is a semi autobiographical depiction of his experience with the Christian Brothers.
O’Nolan writes prodigiously during his years as a student at University College, Dublin (UCD), where he is an active, and controversial, member of the well known Literary and Historical Society. He contributes to the student magazine Comhthrom Féinne (Fair Play) under various guises, in particular the pseudonym Brother Barnabas. Significantly, he composes a story during this same period titled “Scenes in a Novel (probably posthumous) by Brother Barnabas”, which anticipates many of the ideas and themes later to be found in his novel At Swim-Two-Birds.
In 1934 O’Nolan and his student friends found a short-lived magazine called Blather. The writing here, though clearly bearing the marks of youthful bravado, again somewhat anticipates O’Nolan’s later work, in this case his Cruiskeen Lawn column as Myles na gCopaleen. Having studied the German language in Dublin, he may have spent at least parts of 1933 and 1934 in Germany, namely in Cologne and Bonn, although details are uncertain and contested.
A key feature of O’Nolan’s personal situation is his status as an Irish government civil servant, who, as a result of his father’s relatively early death, is obliged to support ten siblings, including an elder brother who is an unsuccessful writer. Given the desperate poverty of Ireland in the 1930s to 1960s, a job as a civil servant is considered prestigious, being both secure and pensionable with a reliable cash income in a largely agrarian economy. The Irish civil service is fairly strictly apolitical, prohibiting Civil Servants above the level of clerical officer from publicly expressing political views. This fact alone contributes to his use of pseudonyms, though he had started to create character-authors even in his pre-civil service writings. He rises to be quite senior, serving as private secretary to Seán T. O’Kelly and Seán McEntee.
Although O’Nolan is a well known character in Dublin during his lifetime, relatively little is known about his personal life. On December 2, 1948 he marries Evelyn McDonnell, a typist in the Department of Local Government. On his marriage he moves from his parental home in Blackrock to nearby Merrion Street, living at several further locations in South Dublin before his death. The couple has no children.