In 2005 J. Michael Hayden and Malcolm Greenshields published 600 Years of Reform: Bishops and the French Church, 1190–1789 (Montreal: McGill-Queen's University Press, 2005), and as Hayden points out, his book is a companion to the more broadly conceived co-authored volume. In Catholicisms of Coutances, Hayden examines in great depth the Norman Diocese of Coutances and the way religion was expressed within it during the early modern period.

In May 1987 Hayden and Greenshelds were on a research trip to Normandy. On Ascension Thursday the archives were closed, and they drove to see the towns whose records they were analyzing. They noticed that in some villages many people attended Mass, and in others few did. Hayden was interested in the patterns of religious practice over time. He found it interesting that research shows that current practice reflects that of 1791, as noted by Timothy Tackett, and Hayden believes the patterns probably go back to seventeenth century (16). He is interested to know when the variations in practice first expressed themselves, and determining this is one of the goals of his book.

Hayden begins his book by asserting that he is not writing a history of the diocese, but rather “a history of the changes in religious beliefs and practices of the people living in that diocese,” and he uses the term catholicisms to encompass the array of religious beliefs expressed by elites and commoners (3). He is interested in religious belief as it was practiced, not prescribed, and he relies upon a number of different primary sources to illuminate religious behavior including records of pastoral visits, ordination lists, diocesan documents, and the cahiers drafted for the 1788 Estates General.

The book is profound in its depth of research and rich quantitative analysis, and is a very impressive scholarly work. Hayden and Greenshields's earlier book relied on pastoral visits and synodal records that were quantified and analyzed. This book has broader array of documentation. In both books Hayden used the sources to produce “an in-depth and thick description of varieties of religious belief in an early modern French diocese” (8). The book is thick in its descriptions of different groups within the community. There are chapters on bishops, clerical elites, members of religious orders, parish clergy, and the Catholic laity. There are more extant materials about elites so they are covered in much more depth, and Hayden discusses the laity from elite to peasant as if they share one religious outlook. Other historians of early modern religious practice and belief have teased out different strands of elite and popular religion, and Hayden's book is limited in this regard.

Hayden defines Catholic reform as coming in two waves. The first from the 1480s to the 1580s, and the second in the eighteenth century. He credits bishops with being the engines propelling reform, and he analyzes each of the diocese's bishops to determine his worth as a reformer. He sees more evidence of reform in the eighteenth century when the clergy became better educated, again he primarily credits the bishops for initiating reform, but also recognizes the influence of the Council of Trent.

The presence of Protestants is evident throughout the book, and it is a constant point of tension as Catholics deal with iconoclastic outbursts including the destruction of a new organ in the cathedral (105). However, in the chapter about Protestants and Deists, Hayden defines them as “other Catholicisms.” The author defines Huguenots in the diocese as “Catholicism without what Catholics called Tradition and without the remnants of paganism that were still attached to Catholicism” (233). Throughout his book Hayden does describe the dangers present for Protestants, especially after 1685 when they were forced to convert or flee France. The Huguenots were not simply other Catholics; they were religious dissidents who suffered for their beliefs. Life would have been much easier for them had they been recognized as living within the Catholic fold.

Hayden develops the idea of Catholicisms, but the reader does not get the sense that there is a great deal of variety in religious practice among Catholics. In the late Middle Ages priests shared the views of the laity, but seminary education became more common in the late seventeenth century. The laity was left with a faith that included traditional superstitions while elites embraced a narrower definition of Catholicism. Hayden concludes that “each person's Catholicism was formed by a combination of personality, health, education, experience, and opportunity,” and this is a statement that would be true at any historical moment (256). The strength of Hayden's books is in its rich details and careful descriptions, and less in its broader conclusions.

Hayden believes that his conclusions about religious practice in Countances can be extrapolated to understand religious change throughout France and western Europe (15). He is no doubt right. Across Europe, Catholics became better educated in their faith and more willing to accept a faith defined by seminary-educated clergy. As Hayden demonstrates, this process occurred over a long period of time, and was influenced by many different groups of people in different dioceses. His thoughtful research and penetrating analysis allow all historians of early modern Europe to appreciate how change unfolded.