Read at the 2005 HES Conference by Don Moggridge, chair of the Spengler Prize Committee: I have an obligation to be brief this evening in awarding the Spengler Prize for the best book in economics. The book is a history of the development of and relationship between two disciplines in the twentieth century -- mathematics and economics. It is a history with a strong biographical, and even an autobiographical twist. It benefits from a somewhat wider disciplinary perspective than most works in the history of economics. Finally, unlike most books in the subject, it even has charm. I am referring, of course, to Roy Weintraub's _How Economics Became a Mathematical Science_ published by Duke University Press. The committee consisted of me, Joe Persky, Steve Horowitz and John Whitaker. [Posted for Don Moggridge by HB.] You can see a history of Spengler Prize winners on the web at http://eh.net/HE/HisEcSoc/book.shtml