Vita Nuova (New Life) is Dante's earliest major work. In Dante's Vita Nuova: A Translation and an Essay (Bloomington, Ind.: Indiana University Press, 1973), translator and editor Mark Musa combines 31 poems with explanatory prose and treats Dante's love for Beatrice Portinari.
Reliable English translations of Dante's lyrics can be found in Dante's Lyric Poetry (2 volumes, translated and with commentary by Kenelm Foster and Patrick Boyde, Oxford: Clarendon Press, 1967)
In Literary Criticism of Dante Alighieri (Lincoln: University of Nebraska Press, 1973), Robert S. Haller has collected, translated and edited Dante's own writings about literature, including the important "Letter to Can Grande,'' in which Dante explains how to read and understand his Divine Comedy.
Saint Augustine's Confessions had a profound influence on Dante. A wonderful translation of this work by R. S. Pine-Coffin (Confessions, by Saint Augustine (354-430), translated by R. S. Pine-Coffin, Harmondsworth: Penguin Classics, 1961) makes this work accessible to students.
The The Consolation of Philosophy by Anicius Manlius Severinus Boethius (4757-525?), a Roman philosopher and statesman, is an important philosophical treatment of free will and predestination—issues examined by Dante in Divine Comedy. The translation of this work by Richard Green is the English standard for students (The Consolation of Philosophy by Boethius, translated and with introduction and notes by Richard Green, The Library of the Liberal Arts, Indianapolis: Bobbs-Merril Co., 1962).
Giovanni Boccaccio and Leonardo Bruni Aretino, authors in their own rights, wrote early biographies of Dante. Boccaccio's came some fifty years after Dante died, and Aretino's followed soon after. The biographies have been translated by James Robinson Smith and can be found in The Earliest Lives of Dante (1901; rpt. New York: Ungar, 1963).
Although Dante did not read Homer's epic The Odyssey, he knew its basic plot, was influenced by it and, like most readers, was probably awed by Homer's genius. Odysseus' trip to the Underworld, the realm of dead souls, influenced Virgil whose Aeneid was Dante's poetic model. A good translation of The Odyssey is by Robert Fitzgerald (New York: Vintage Classics, 1961, 1963).
John Milton's Paradise Lost, the great Protestant epic of the seventeenth century, tells the story of Adam and Eve's fall from grace and is in some ways a commentary on Dante's Catholic Comedy. Scott Eledge's edition of Paradise Lost is an excellent one (New York: W. W. Norton, 1975).
Any reader of Dante's work needs a good Bible, one with solid notes and cross references. The New English Bible with the Apocrypha: The Oxford Study Edition (general editor, Samuel Sandmel, New York: Oxford University Press, 1976) is an excellent edition for student use.
Virgil leads Dante's Pilgrim through Hell and to Beatrice in Purgatory. Virgil's own epic tale, The Aeneid, tells the story of Aeneas' founding Rome. This work, along with much of Virgil's poetry, had a profound impact on Dante. Aeneas' trip to the Underworld in Aeneid 6 was a model for Dante's Pilgrim's trip through hell. A fine translation of Virgil's epic is The Aeneid of Virgil, translated by Allen Mandelbaum, 1961 (reprint, New York: Bantam Books, 1985).