 He received his Ph.D. from Indiana University and has held teaching positions at the University of Kansas, the University of California, Los Angeles, and Washington University in St. Louis.He has served as president of the International Arthurian Society.With Geoffrey Ashe he wrote "The Arthurian Handbook", and he edited "The Arthurian Encyclopedia" and its successor, "The New Arthurian Encyclopedia", a standard reference book for Arthurian works.