The Fermat Little Theorem and the Wilson Theorem are known to beginners in Number Theory. In 1956, Leo Moser discovered a congruence (modulo a prime p) that encompasses these two results. Almost 40 years later, William Moser (the younger brother of L. Moser) discovered a generalization of L. Moser's congruence that holds true for arbitrary positive integer n. In this talk, we will present this generalization, which we shall name as the Moser-Moser congruence.