Since the last biographies of Luther in English appeared, nearly ten years ago, a vast amount of light has been shed on the subject by the discovery of new documents and by the intensive research of a great army of the learned. A special stimulus was supplied to their zeal by the celebration of the Reformation quadricentenary in 1917; and the fact that America was cut off from Germany for four years out of the last ten, and that the books of her production have only begun to reach us in large numbers, may add another reason, were it necessary, for offering an extensive review of the outstanding work in this field since the end of the year 1910. For the sake of convenience the more detailed studies will be taken up first, in the chronological order of events in Luther's life; the more general collections of works, bibliographies, biographies, and estimates, will follow after.