During his studies, he developed a strong interest in Ulster Irish, and often visited the Irish-speaking Gola Island and Derrybeg.
Quin compiled the folklore of native Irish speakers from the islands of Tory and Arranmore off the coast of County Donegal, including Róise Mhic Ghrianna.
In 1961, he was appointed professor of Biblical Greek at Trinity College, and began work on a new translation of the New Testament.
He also translated the Book of Psalms, the Prayer Book of the Church of Ireland and the Apocrypha into Irish, as well as theological works by Walter Eichrodt and Rome and Canterbury: A Biblical and Free Catholicism by Emmanuel Amand de Mendieta.
[4] Although it was unusual in his lifetime for Protestants to hold leading positions in the Irish language movement, Quin was for a time President of Oireachtas na Gaeilge.