His father was the American diplomat James Hugh Keeley. He spent his childhood in Canada, Greece, and Washington, D. C. before earning his B.A. from Princeton University in 1948. In 1952 he received a Doctorate in Comparative Literature from Oxford University where he studied with a fellowship from the Woodrow Wilson National Fellowship Foundation.

He served as president of PEN American Center from 1992 to 1994.

He retired from a long career at Princeton University in 1994.

• Rome Prize, American Academy of Arts and Letters (1959)
• New Jersey Authors Award:

• (1960) For the novel The Libation (Citation)
• (1968) For George Seferis: Collected Poems, 1924-1955
• (1970) For the novel The Impostor

• Guinness Poetry Award selection, 1962
• National Book Award in Translation (finalist) 1973
• P.E.N.-Columbia University Translation Center Prize (1975)
• Harold Morton Landon Translation Award, Academy of American Poets (1980)
• Howard T. Behrman Award for Distinguished Achievement in the Humanities (1982)
• PEN/National Endowment for the Arts Fiction Syndicate Award (1983)
• Pushcart Prize Selection (1984—85)
• First European Prize for Translation of Poetry (1987)
• National Translation Award (Citation) (1992)
• Honorary Doctorate, University of Athens (1994)
• Academy Award in Literature (1999)
• PEN/Ralph Manheim Medal for Translation (2000)
• Criticos Prize London Hellenic Society (2000)
• Commander of the Order of the Phoenix (2001)
• The Yale Review Prize (2003)
• Trustees’ Annual Award, Gennadius Library (2003)
• Phidippides Award (2004)
• Honorary Doctorate, Richard Stockton College (2006)
• Dido Sotiriou Cultural Prize, Hellenic Authors' Society (2008)
• Lord Byron Award, Hellenic College, (2008)