As in Europe, secular nation building in Latin America challenged the traditional authority of the Roman Catholic Church in the early twentieth century. In response, Catholic social and political movements sought to contest state-led secularisation and provide an answer to the 'social question', the complex set of problems associated with urbanisation, industrialisation, and poverty. As Catholics mobilised against the secular threat, they also struggled with each other to define the proper role of the Church in the public sphere. This study utilizes recently opened files at the Vatican pertaining to Mexico's post-revolutionary Church-state conflict known as the Cristero Rebellion (1926-1929). However, looking beyond Mexico's exceptional case, the work employs a transnational framework, enabling a better understanding of the supranational relationship between Latin American Catholic activists and the Vatican. To capture this world historical context, Andes compares Mexico to Chile's own experience of religious conflict. Unlike past scholarship, which has focused almost exclusively on local conditions, Andes seeks to answer how diverse national visions of Catholicism responded to papal attempts to centralize its authority and universalize Church practices worldwide. The Politics of Transnational Catholicism applies research on the interwar papacy, which is almost exclusively European in outlook, to a Latin American context. The national cases presented illuminate how Catholicism shaped public life in Latin America as the Vatican sought to define Catholic participation in Mexican and Chilean national politics. It reveals that Catholic activism directly influenced the development of new political movements such as Christian Democracy, which remained central to political life in the region for the remainder of the twentieth century.

Who was the "Mysterious Sofia," whose letter in November 1934 was sent from Washington DC to Mexico City and intercepted by the Mexican Secret Service? In The Mysterious Sofia Stephen J. C. Andes uses the remarkable story of Sofia del Valle to tell the history of Catholicism's global shift from north to south and the importance of women to Catholic survival and change over the course of the twentieth century. As a devout Catholic single woman, neither nun nor mother, del Valle resisted religious persecution in an era of Mexican revolutionary upheaval, became a labor activist in a time of class conflict, founded an educational movement, toured the United States as a public lecturer, and raised money for Catholic ministries-all in an age dominated by economic depression, gender prejudice, and racial discrimination. The rise of the Global South marked a new power dynamic within the Church as Latin America moved from the margins of activism to the vanguard. Del Valle's life and the stories of those she met along the way illustrate the shared pious practices, gender norms, and organizational networks that linked activists across national borders. Told through the eyes of a little-known laywoman from Mexico, Andes shows how women journeyed from the pews into the heart of the modern world.

Who was the "Mysterious Sofia," whose letter in November 1934 was sent from Washington DC to Mexico City and intercepted by the Mexican Secret Service? In The Mysterious Sofia Stephen J. C. Andes uses the remarkable story of Sofia del Valle to tell the history of Catholicism's global shift from north to south and the importance of women to Catholic survival and change over the course of the twentieth century. As a devout Catholic single woman, neither nun nor mother, del Valle resisted religious persecution in an era of Mexican revolutionary upheaval, became a labor activist in a time of class conflict, founded an educational movement, toured the United States as a public lecturer, and raised money for Catholic ministries-all in an age dominated by economic depression, gender prejudice, and racial discrimination. The rise of the Global South marked a new power dynamic within the Church as Latin America moved from the margins of activism to the vanguard. Del Valle's life and the stories of those she met along the way illustrate the shared pious practices, gender norms, and organizational networks that linked activists across national borders. Told through the eyes of a little-known laywoman from Mexico, Andes shows how women journeyed from the pews into the heart of the modern world.