Leon’s professional accomplishments were impressive. He taught atLong Island University and held numerous other prestigious academic posts. He had a private therapeutic practice. He served as Chief of Behavioral Medicine at the Brooklyn VA Medical Center. He founded the International Academy of Preventative Medicine. He published extensively in prestigious journals. His work appeared in the Proceedings of the National Academy of Sciences. He edited the Handbook of General Psychology, a multi-volume encyclopedic series on psychology. His book, The New Science of Axiological Psychology, integrated philosopher Robert Hartman’s formal theory of axiological science with cognitive psychology. Leon applied scientific principles to rank human values and to predict human behavior using his science of values approach.