Historians of colonial Mexico generally stress the importance of the Catholic Church and religious culture. However, too often we fail to demonstrate just how this was manifested in society. Matthew O'Hara has produced an exemplary study focused precisely on detailing the intertwining of devotional practice, race, identity, parish affiliation and the everyday politics of Mexico City in the late eighteenth and early nineteenth centuries. In the process, he sheds considerable light on why religious culture and ethnic identities forged in the colonial era proved resistant to change. The book is divided in three parts. In the first, O'Hara provides an overview of the Church's structure and function in colonial Mexico City, and traces the emergence of reformist ideas that challenged interconnected religious and social norms. This portion is crucial because it sets out how ethnic identity was built into parish formation, and colonial subject formation, from the very beginning. In short, the marking of boundaries in the social world and the realm of religious affiliations were inextricably linked. Thus residence in specific parishes, membership in certain lay institutions, taking part in particular forms of public piety denoted indigenous and Spanish identity in the city. We then learn how eighteenth-century Bourbon reformers sought to suppress the baroque sensibilities and identities of the populace and replace them with a rationalised, staid, more homogeneous religious culture. These aspects of modernising reformism are not new to historians, but O'Hara puts meat on the bones of our understanding, particularly in part ii of his book. Here he presents evidence on the varied responses to reformist endeavours. It is quite wonderful to read about the real people, priests and laypersons, caught up in – and stirred by – issues of parish jurisdiction, notions of ownership regarding church structures, efforts to ‘clean up’ devotional practice, and relatively mundane religious fundraising. In the third, and final, section of the book the author details how many of these concerns and patterns endured well into the nineteenth century. Here O'Hara demonstrates how the new order's ostensibly more secular foundations were in reality built on colonial parish structures. As a result the ethnic and racial identities fused to religious and political structures carried over as well. In sum, this book represents a very important contribution. Scholars seeking extensive discussions of the theological debates or high-level ecclesiastical politics should look elsewhere. Here, though, is a fine example of how the sensitive and creative analysis of historical documentation generated by a complex religious institution can give us a vivid sense of life in the past.