Pastoral: Mediaeval into Renaissance (D.S. Brewer, 1978)
The Structure of the Canterbury Tales (Duckworth; U of Georgia Press, 1983)
Oxford Guides to Chaucer: The Canterbury Tales (Oxford University Press, 1989, 1996)
The English Romance in Time: Transforming Motifs from Geoffrey of Monmouth to the Death of Shakespeare (Oxford University Press, 2004)
Shakespeare and the Medieval World (Arden Companions to Shakespeare, 2010)
The Long Fifteenth Century: Essays for Douglas Gray, co-edited (Oxford University Press, 1997)
Medieval Shakespeare: Pasts and Presents, co-edited (Cambridge University Press, 2013)
Sir Thomas Malory: Le Morte Darthur – The Winchester Manuscript, modern-spelling edition (Oxford World’s Classics, 1998)