This section of the American Psychologist was prepared to celebrate the centenary of the publication of Edward L. Thorndike's 1898 doctoral dissertation, "Animal Intelligence: An Experimental Study of the Associative Processes in Animals." The author explores Thorndike's life and work in animal psychology, educational psychology, and mental testing. Thorndike was a "sane positivist," who believed strongly in the scientific method and the application of the results of scientific research for the betterment of humanity.