Oakley was born and raised in England and served as a lieutenant in the British Army. He was educated at Oxford University (B.A./M.A. – First Class Honours), the Pontifical Institute of Medieval Studies, Toronto, Canada, and Yale University (M.A., Ph.D.) He holds honorary degrees, LL.D., L.H.D. and Litt.D. from Notre Dame, Northwestern and Wesleyan Universities, from North Adams State College, and from Amherst, Bowdoin and Williams Colleges.
Oakley is a former president of Williams College, the New England Medieval Conference (1983-84) and the Fellows of the Medieval Academy of America (1999-2002). He was chairman of the boards of ACLS (1993-97), the Sterling and Francine Clark Art Institute (1998-2005), and the National Center for the Humanities, North Carolina (2004-2007). He is a Fellow of the Medieval Academy of America and of the American Academy of Arts and Sciences, and an Honorary Fellow of Corpus Christi College, Oxford.