This is a book of interest to the observer of the liberal scene in America and an important contribution to the history of American political thought. Professor Warren, of Queens College in New York City, has attempted ""to gauge the nature and extent of Communist influence on liberal thinking in the thirties"" through an exhaustive examination of the contemporary writings of a broad cross section of those liberal intellectuals then ""free from restrictions of public office"" (e.g. magazine editors, political commentators, free lance writers, educators, etc.). It is Professor Warren's thesis that this erudite band, far from being the monolithic but gullible front they are traditionally accused of having been, were in fact divided into at least three distinct groups: the fellow travelers, the Russian sympathizers and the anti-Communist liberals. Each of these groups is examined and distinguished through an assessment of its published responses to the major issues or events of the thirties. The synthesis achieved by this matrix technique, while ingenious, tends to be somewhat mechanical in its relentless cataloging of all the permutations and leads to some monotonous reading. However, in finally laying to rest the myth that all American liberal thinking of the thirties was dominated by the Communists, this book can fairly be called definitive.