Prof. Foster has studied Tolkien manuscripts and other papers at Marquette University in Milwaukee and at the Bodleian Library in Oxford. He has also studied C.S. Lewis and Tolkien letters and other material at the Marion E. Wade Center, Wheaton College, Wheaton, Illinois. He has presented and published papers on those studies at various conferences in the United States and England.

Among Foster's studies have been “The Ulsterior Motive,” a view of the religious differences between Tolkien and Lewis; “Hobbits and Hogwarts Go Hollywood: Fantasy Fiction to Fantasy Film”; longer studies of Tolkien’s manuscript revisions of The Hobbit and The Lord of the Rings; The Forest and the Hall, a short study of Tolkien's last complete story, Smith of Wooton Major; The Shire & Notting Hill: J.R.R. Tolkien & G.K. Chesterton; Ringo and Samwise: Paradigms?, a comparison of Tolkien’s four hobbits and the four Beatles; An Unexpected Party: Tolkien in the 1960s; J.R.R. Tolkien: Fiction to Film; and Peter Pan: The Lost Last Act, a study of an unused original ending to that play found in the Lilly Library at Indiana University.

He has served as the North American representative of the Tolkien Society (Great Britain) since 1995. He was elected to the board of directors of the American Chesterton Society in 1997 and contributes a book review column, “Off the Shelf,” to the Society’s magazine Gilbert! He is a member of the Mythopoeic Society scholarship awards committee.

Named faculty advisor of the College’s Harbinger student newspaper in 1973, Foster has continued in that post since. He is a charter member and current provisional president of the Illinois Community College Journalism Association. As a freelance writer, he has published articles and reviews in Living Blues, The Washington (D.C.) Weekly, The Peoria Journal Star, Christian History, Mythprint, Sunrise, The Prairie Sun, P.O.P, Faith & Reason, Amon Hen, and Mallorn. He graduated from Marquette University with a double major in English and journalism and a philosophy minor in 1968 and a M.A. in English in 1971.