Alonzo Church was undeniably one ofthe intellectual giants of theTwenti eth Century . These articles are dedicated to his memory and illustrate the tremendous importance his ideas have had in logic, mathematics, comput er science and philosophy . Discussions of some of thesevarious contributions have appeared in The Bulletin of Symbolic Logic, and th e interested reader is invited to seek details there . Here we justtry to give somegener al sense of the scope, depth, and value of his work. Church is perhaps best known for the theorem, appropriately called " C h u r c h ' s Theorem," that...