The opening of the different Vatican Archives for the pontificate of Pius XII (1939-1958) in March 2020 sparked the interest of scholars across different disciplines worldwide. It invigorated tendencies to revisit the history of the 1940s and 1950s beyond the established narratives and sources, and nourished hopes to address both longstanding and emerging questions, and to discover innovative themes and approaches. Three years after the opening of these archives, a multidisciplinary group of scholars from Belgium and the Netherlands convened at a scientific conference in Rome, organized by the editors of this volume, to study the impact of the archival access on diverse research domains. This publication presents new research based on documentation unearthed in the Vatican archives, spanning both the Second World War and the postwar period and challenges existing scholarship not only on the history of the Catholic Church, but also on broader themes in the Low Countries.