He won a scholarship to attend St. Andrew's School in Delaware for a year before reading history at Trinity College Dublin.
and PhD by Trinity College, where he was taught by T. W. Moody and F. S. L. Lyons, and was elected a scholar in History and Political Science in 1969.
Prior to his appointment to the Carroll professorship, he was Professor of Modern British History at Birkbeck College, University of London, and held visiting fellowships at St Antony's College, Oxford, the Institute for Advanced Study, Princeton, and Princeton University.
He collaborated with Fintan Cullen on a National Portrait Gallery exhibition, Conquering England: the Irish in Victorian London.
[2] Foster produced a much-acclaimed two-part biography of W. B. Yeats,[3][4] which was awarded the James Tait Black Memorial Prize.