In her youth, she was sent to Italy to live with relatives, attending Les Dames de Scion convent in Rome.
When she returned to Dublin she lived alternately with her grandfather and aunts in Dartmouth Square, and in Ballyboden and later Rathgar with her parents.
[1] Byrne-Costigan was appointed professor of Romance languages at University College Cork (UCC) in 1939, after the retirement of Mary Ryan.
Her academic publications focused on studies of Le bourgeois gentilhomme by Molière, Athalie by Jean Racine, and Horace by Pierre Corneille.
[1][2] She retired from UCC, taking up part-time lecturing at Trinity College Dublin on Italian philology and medieval texts.