This is great fun: A distinguished research mathematician, known (among other things) for the expository clarity of his writing, returns in his seventh decade to his "first love, baseball." "Returns" is perhaps the wrong word. It is clear from his account of his gradeschool days, when he taughthimself long division computing batting averages by flashlight under the covers at night, that Ken Ross' infatuation with our national pasttime has been steadfast and faithful.Cheerful and idiosyncratic, this book approaches inmathematical rigor the standards required of a formal college-level introduction to such topics as Bernoulli trials, betting strategies, correlation, expectation, odds, probability (including conditional probability), statistical significance, and strategies---all in the engaging context of anecdotes and data drawn from the world of baseball. Thus the book reads equally well from two perspectives: as a self-contained introduction to sophisticated mathematical concepts, motivated and spiced by carefully chosen anecdotes and examples from ``the real world" of professional sport; and as an extended focus on baseball itself, sprinkled with countless examplesof how an appreciation of mathematics and statistics can enhance one's enjoyment of the game. (As a sportingenthusiast and a professional mathematician, I thought I knew about all there was to know about this interaction. But the day after reading Ross' book I happened to find myself in a Connecticut bar watching TV while the Yankees and the Red Sox beat up on each other yet again. The story line was familiar, but my eyes and ears were attuned as if to a new experience. New riches, subtleties and nuances were mine to appreciate, thanks to this stimulating book. Despite decades of first-handexperience, I found myself recollecting the question raised byCole Porter in a very different context: ``How long has this been going on?")Amazon.com sent me this book for \$13.96 plus postage. That was money very well spent.