Green received a B.S. in economics in 1948, finishing his undergraduate degree in just over two years and graduating with honors. He enrolled at Temple Law School as one of ten black students, of whom two would ultimately graduate (the other graduate, Larry Perkins, would also go on to become a judge). While in law school Green was a member of the moot court team and the law review. He competed on a moot court team which won the Philadelphia regional of the American Bar Association competition. At the national competition, Green's team faced the Yale moot court team, which included his future law partner and judicial colleague A. Leon Higginbotham, Jr.. In 1951 Green received his LL.B. with honors, graduating in the top three of his class. He was also awarded graduation prizes for receiving the highest grades in constitutional law and conflicts of law.