This is a source edition for those interested in plenary indulgences and the Holy Roman Empire in the Middle Ages. As the editor states in the introduction, it is unclear why these documents have not previously been edited and printed systematically, since without knowing their precise content, it is impossible to fully understand the dynamics that led to Luther's criticism of papal indulgences and to the birth of the Reformation movement. This book, published soon after the five-hundredth anniversary of the Reformation, finally fills this gap.

The book begins with a useful introduction, in which the editor explains the publishing of the edition and puts the documents and the scholarly tradition around these texts into their respective historical contexts. He also explains which documents were chosen for the edition and why: the book contains a full text edition of all existing papal bulls and letters between 1300 and 1517 which concern plenary indulgences in the German Reich. The edition includes not only the papal indulgence bulls but also instructions for indulgence commissars and documents related to the extension of the papal indulgence campaigns in the Regnum Teutonicum.

The edition is based on printed texts from different European libraries and archives, not on the handwritten copies in the papal copybooks in the Archivo Segreto Vaticano. Such a decision might seem strange but Jenks gives a reasonable explanation for his choice: the originals in the papal collections often differ somewhat from the texts that were eventually printed locally. For the purpose of this edition, it is therefore more sensible to use the variants that circulated in German territory. The edition includes plenary indulgences related to the jubilees celebrated in Rome (1300, 1350, 1389, 1400, 1425, 1450, 1475 and 1500), to various crusade campaigns (both against Muslims in Near East and heretics within the borders of European nations, such as the Hussite wars), to the building of St Peter's in Rome as well as to some special local events which the popes wanted to support.

The introduction is followed by ‘A brief guide for the uninitiated’, which is meant for readers who are not familiar with the history of indulgences and the medieval theological thinking behind them. The guide begins with a concise explanation of the concept and history of indulgences and their relationship to sin, penance, purgatory and absolution as well as to the papal powers to absolve Christians from different kinds of sins. Then follows an overview of the history of the indulgences related to the medieval jubilees of the Catholic Church and a short description of the role of Raymundus Peraudi in the development of the formulation of the indulgences. There is then an explanation of how the crusading indulgences changed form during the centuries from the formulation of the Fourth Lateran Council in 1215 until the beginning of the sixteenth century. After that the author explains the relationship between the documents of the Apostolic Penitentiary and plenary indulgences and finally the late (early sixteenth-century) development of plenary indulgences.

This part of the book is very short and the author cannot go into details but the chapter is nevertheless useful for readers who are not familiar with papal indulgences. However, the description is not always up-to-date, especially in its description of the relationship between the Penitentiary documentation and the indulgences. It would have been useful to stress that the Penitentiary documentation also contains a lot of material not relevant to plenary indulgences. Also, although the author correctly uses statistics compiled by Ludwig Schmugge for the Regnum Teutonicum, he claims (wrongly) that no statistical information is available from France. Schmugge and Salonen have published Penitentiary statistics from all regions of Europe in many different places.

After the forty-page introductory material comes the edition (pp. 41–753), which is divided into twenty-seven chapters each of which contains the documentation relevant to one specific group of indulgences, including their different extensions and local variants of the original indulgence. The edition works chronologically, beginning with the indulgence for the first jubilee celebrated in Rome in 1300 under the auspices of Pope Boniface viii (chapter i). The jubilee indulgences of the years 1350, 1389, 1450, 1475 and 1500 are also included in the edition (chapters ii, iii, vi, x and xv), as are a large number of crusading indulgences. Four of the latter promote crusades against the Turks (in 1455, 1463, 1489 and 1501/3 [chapters vii, viii, xiv and xvi]) and four crusades against European heretics (Hussites 1420, Podiebrad and Bohemians 1465/71, Russians and Tartars in Livonia 1503/06 and 1507/10 [chapters iv, ix, xvii and xix]). In addition, the edition includes indulgences for the construction of St Peter's from 1506, 1514/18 and 1516/18 (chs xviii, xxvi and xxvii) as well as a number of indulgences promoting local churches or monastic orders like the church of Saintes in 1476/88 (ch. xi) or the repair of the dykes in the Burgundian Netherlands in 1515/18 (ch. xxiv). The editions have been prepared to MGH standards and provide, in addition to the full text, a short summary or title and bibliographical information about where the original documents can be found and where they have been edited.

The volume closes (pp. 754–70) with a conclusion which discusses the economy of the indulgences – a topic initially criticised by Luther in his theses. This very interesting short chapter is followed by a useful chronological list of documents, a literature list as well as a person and place name index.