George H. Williams, professor in the Harvard Divinity School, in his expansive volume The Radical Reformation states in his introduction that ""there is no aspect of sixteenth century research that is so alive with newly discovered and edited source materials and monographic revisions as the Radical Reformation."" This statement by Dr. Williams is amply proved in a very extensive and remarkably interesting and readable account of this phase of the Reformation. The pressure of today's ecumenicity should make this important and vital reading for anyone wishing to understand adequately the grass roots of the spiritual forebears of many of today's Protestants. Particularly fascinating is the intense struggle between men like Luther and Zwingli, representatives of the Magisterial Reformation and the extreme Anabaptists. Although the abundant material in this book is needed by any serious student of the Reformation its cost will doubtless lead most to seek it in the public or seminary library.