He attended University College Dublin where he completed a BA 1963 and an MA 1964.
[1] Though his Irish roots are clear in his poetry, Grennan has an international sense of literary tradition.
In addition to writing poetry, he has translated Giacomo Leopardi and—with his wife, Vassar classicist Rachel Kitzinger—Sophocles's Oedipus at Colonus.
Grennan studied English and Italian at University College, Dublin, where he met poets Derek Mahon and Eavan Boland, and at Harvard University, and began teaching at Vassar in 1974.
Poet Laureate Billy Collins said of Grennan: He received the PEN Award for Poetry in Translation in 1998.