This work investigates the complex evolution of the Spanish Catholic Church as it navigated a century of radical political instability and social transformation between 1875 and 1975. Frances Lannon, a scholar of modern Spanish history, utilizes extensive ecclesiastical archives and primary source documentation to analyze the Church's shifting role from a privileged state institution to a survivor of civil conflict and authoritarian rule. The book argues that the Church did not merely react to external pressures but actively shaped and was fundamentally reshaped by the turbulent political landscape of the Bourbon restoration, the Second Republic, the Civil War, and the Franco dictatorship.

Historians and scholars of Spanish history frequently cite this work as a definitive account of the institutional and social history of the Church during a critical century. Readers often note the academic rigor and the depth of archival research, which provides a balanced view of the Church's multifaceted role in Spanish life.