He enrolled in the Graduate School of Harvard University in 1947, completing his Ph.D. in history in 1953, meanwhile serving as concertmaster of the Harvard-Radcliffe Symphony Orchestra.
After his son John joined the Yale economics faculty in 1980, they became only the third father-son pair to be tenured professors concurrently in the university’s history.
[1] Geanakoplos's numerous books include: Emperor Michael Palaeologus and the West, 1258-1282: a study in Byzantine-Latin relations (Harvard University Press, 1959), Greek scholars in Venice: studies in the dissemination of Greek learning from Byzantium to Western Europe (Harvard University Press, 1962), Byzantium and the Renaissance: Greek scholars in Venice: studies in the dissemination of Greek learning from Byzantium to Western Europe (Archon Books, 1973), Interaction of the "sibling" Byzantine and Western cultures in the Middle Ages and Italian Renaissance: (330-1600) (Yale University Press, 1976), Medieval Western Civilization and the Byzantine and Islamic worlds: Interaction of three cultures (D.C. Heath, 1979), Byzantium: Church, Society, and Civilization Seen Through Contemporary Eyes (University of Chicago Press, 1984), Constantinople and the West: Essays on the Late Byzantine (Palaeologan) and Italian Renaissances and the Byzantine and Roman Churches (University of Wisconsin Press, 1989).
[3][4][2] His research showed the pivotal role that Byzantine scholars who emigrated to Italy played in unlocking and interpreting ancient Greek texts vital to the Italian Renaissance, systematically documenting their interactions in the West.
[2] He was married to Effie Geanakoplos, a clinical social worker and instructor in psychiatry at the Yale Child Study Center, for 48 years.