2025 Catholic Media Association Honorable Mention, Ecumenism or Interfaith RelationsMutual recognition of baptism has grounded ecumenical efforts, but does contemporary Roman Catholic pastoral practice reflect these ecumenical theologies? How do we understand the outer boundaries of the church? On the one hand, over the centuries Christians have recognized the baptism of those outside their own ecclesial body, but on the other hand, the practices of receiving those who are already baptized from other groups proclaim social, theological, and ecclesial distinctions. How do contemporary practices reflect theological principles and historical development? One Baptism-One Church? demonstrates ways that contemporary practice may be an obstacle to the full expression of our ecumenical commitments and how history can reshape that practice. While the mutual recognition of baptism has grounded ecumenical efforts, pastoral practice-especially in local communities far away from the centers of power-does not always reflect ecumenical theologies. Contemporary Roman Catholic practice may seem at odds with the official understanding of baptized Christians as in real though imperfect communion by means of their participation in Christ. Focusing on the Byzantine East and Roman West, this book seeks to remove obstacles to the more complete expression and recognition of Christian unity and outlines concrete ways that our partial communion could be better expressed. It concludes with practical reflections and recommendations for best practices in the reception of baptized Christians in the contemporary Roman Catholic Church and proposes a reformed Rite for the Reception of Baptized Christians that is more faithful to history and ecumenically sensitive.