This presentation explores the pivotal role of Catholic lay women in shaping religious reinvention and social change during the post-war period (1945-1962). Focusing on the World Union of Catholic Women's Organisations (WUCWO), it examines the transformative impact of their global apostolic work on both the Church and broader society. The international activities of the WUCWO in the 1950s underscore the significance of gender and interfaith perspectives in understanding religious reinvention and its broader societal impact. Drawing on historical approaches to religious reinvention, this study analyses how these lay women navigated the tensions between tradition and modernity, reinterpreting Catholic doctrine to address pressing global challenges such as decolonization, Cold War politics, developmentalism, and interreligious dialogue. By framing their efforts as an embodiment of the Church's mission to "renew the face of the Earth" (Psalm 104:30), Catholic lay women acted as transnational experts, redefining notions of human dignity, the laity, and the role of women in society and within ecclesial communities. Their global apostolate in international organizations, including the United Nations and its agencies, fostered spaces for cross-confessional encounters, contributing to the gradual emergence of an ecumenical idea of sorority. This presentation highlights how these women not only reinforced but also reimagined the role of women in late modern societies and Catholicism, paving the way for the social and religious transformations of the 1960s, including the Second Vatican Council.