With this impressive and demanding piece of scholarship, Timothy J. Wengert makes accessible to English readers a theologically most important controversy, the debates fought out in Lutheranism between Luther's death and the Formula of Concord. This is the first monograph dedicated to the controversy over Andreas Osiander's theology of justification in forty years (since the books by Martin Stupperich and Jörg-Rainer Fligge in the early 1970s and since the publication of the final two volumes of the Osiander Gesamtausgabe [ed. G. Müller and G. Seebaß] in 1994/1997). While the Gesamtausgabe contains only Osiander's own contributions to the debate, Wengert's study takes into account all printed pamphlets against Osiander which were published between 1549 and 1567: more than 100 different texts in both Latin and German, comprising thousands of pages. The book consists of an introduction and eight chapters, which discuss certain parts of the debate systematically, so that they do not necessarily have to be read as a continuous narrative. The first two chapters cover the origins of the controversy after Osiander's arrival in Königsberg in Prussia in 1549 and the mounting protest among the Lutherans both in Prussia and in the whole Holy Roman Empire against his understanding of essential justification through the indwelling of Christ, as formulated in Osiander's confession De unico mediatore of 1551. Chapter iii focuses systematically on the concepts of justification advocated by Osiander's different Lutheran critics. Chapter iv features his three main opponents, Mörlin, Flacius and Gallus, who together wrote about a third of all publications against Osiander, while chapter v is devoted to the differing reactions of Melanchthon and Brenz. In chapter vi Wengert examines how Luther was used as an authority within the debate. Chapter vii concentrates particularly on Melanchthon's theological response. The final chapter is an eighty-page strong bibliographic essay which discusses all the tracts against Osiander in chronological order with accompanying bibliographical information (unfortunately the prints are not identified by their VD16-numbers) and short summaries – immensely valuable for future research. In all his chapters, Wengert follows his agenda of showing how unanimously nearly all Evangelical theologians defended Melanchthon's concept of forensic justification over against Osiander, despite the bitter debates among themselves on other parts of Lutheran doctrine. His intention is to ‘examine the process of confessionalization from a rigorously theological point of view’ (p. 4) and to describe the dispute as a struggle over authority – the authority of Luther, Scripture, the University of Wittenberg, and the judgements of individual churches.The author discusses almost every tract in detail, backing his thorough and subtle theological interpretations with speaking quotations (in translation with full original German or Latin text in the footnotes) and succinct, sometimes witty evaluations. Despite its sometimes light-hearted tone and its didactical strengths, the book is not an easy read: many presuppositions and obstacles remain for readers not completely familiar with German (church) history, and the systematic structure leads to various cross-references to other chapters. Wengert's book is not and does not claim to be an account of the whole Osiandrian controversy. It declaredly presents Osiander's theology only as understood and referred to by his critics. It has a clear focus on theology and is restricted to (an overwhelming amount of hitherto almost unknown) printed sources. Thus, in order to obtain a comprehensive picture of the debate, one still has to read the older studies by Stupperich and Fligge which incorporate the archival evidence from Königsberg (today in Berlin), the course of events and the political dimension of the questions at stake. The focus on printed material neglects other forms of the debate, like letters, sermons and pasquills, especially at the local level in Königsberg. As a consequence of this approach, Wengert in my opinion underestimates the role of Duke Albert of Prussia, thus reducing the weight of his argument about the political versus theological dimensions of the confessionalisation process. By describing the debate completely from the perspective of Osiander's critics, it sometimes becomes difficult to understand why Osiander found supporters at all, at the court in Königsberg as well as among the theologians in Prussia and in Nuremberg. This criticism notwithstanding, Wengert has written a rich, thought-provoking study which constitutes a major contribution to the re-evaluation of the theological debates of the second half of the sixteenth century.