Book excerpt: Through an ethnographically driven study of expressions of sanctuary in San Francisco, Church as Field Hospital constructs an ecclesiology that expands notions of public engagement and sacred space in Christian theology. Sanctuary practices that create spaces for those who have been marginalized—immigrants, refugees, and unhoused people—reflect the field hospital church Pope Francis has envisioned and enacted. This book investigates sanctuary as a way of being church, one marked by prophetic witness, embodied solidarity, sacramental praxis, and radical hospitality.