Maurice received Bachelor of Arts at City College of New York in 1923, and Master of Arts at Columbia University in 1924. Then he earned Bachelor of Laws at Columbia University in 1927, and Doctor of Philosophy there in 1939. In 1975 he became Doctor of Letters at Long Island University.
Valency was a professor of comparative literature at Columbia and also taught dramatic literature at Juilliard and at Brooklyn College. While an associate professor at Columbia University, Valency adapted Giraudoux’s "The Madwoman of Chaillot", for which he received his first award in 1949. He followed this with adaptations of another of Giraudoux’s plays, "Ondine", and Durrenmatt's "The Visit", among others.
Maurice also wrote adaptations of librettos and television plays, including “Feathertop” and “The Man Without a Country” for CBS. He wrote several criticisms and novels, including "The End of the World: An Introduction to Contemporary Drama", "The Cart and the Trumpet: The Plays of George Bernard Shaw", "Julie", and "Tragedy."
Maurice spoke seven languages and read even more.
On December 25, 1936, Valency married the artist Janet Cornell; they remained married for 60 years until Valency's death in New York City at the age of 93.