One of the great tasks of Mortimer Adler’s illustrious life was his search for a watertight proof of the existence of God. Adler believed that his search had been successful. Adler spent years studying the classic proofs of God’s existence, especially Aquinas’s Five Ways, and found shortcomings in all of them, as conventionally understood. But he thought that some of them contained ideas which, if properly developed, could be improved, and he continued to search for a satisfying and logically unassailable proof. Toward the end of the 1970s, he believed he had arrived at such a proof, which he presented in his historic work, *How to Think about God* (1980). In the writings assembled in *How to Prove There Is a God* , Adler gives us his approach to the question of God’s existence in fresh and popular form. He defends his position against critics, both believers and skeptics. The book includes a transcript of one of Adler’s appearances on William Buckley’s *Firing Line* , Adler’s revealing interview with Edward Wakin, the exchange of views on natural theology between Adler and Owen Gingerich, and John Cramer’s eloquent argument that the trend of modern cosmology supports Adler’s early struggles with the question of God’s existence.