ChrIs-cross will produce the first comprehensive study of Christianities in Jerusalem and the Middle East from the 12th to the 16th c., in the face of shifting rulership structures, first Frankish, then Islamic, and religious affiliations. It will envisage them from a bottom-up, practice oriented and connected perspective, on the assumption that inter-Christian and Christian-Muslim relations were more conductive to fluidity than to boundary-setting. A multidisciplinary and multilingual team will study a forgotten and so far, inaccessible archive—the archives of the Christian Patriarchates in Jerusalem—and develop an overarching database including interactive maps and editing texts. Open-access metadata will be in English and Arabic. In so doing, it will resituate the history of Christianities within the Islamicate world by reassessing the concept of “minority”, historicise communities’ construction by comparing conquest-induced reconfigurations, with and without a change in religious dominance, and spatialise these processes by examining their interplay, with Jerusalem as a specific urban space in tension with the wider regional area. The project has three main objectives: it aims to address the currently compartmentalised academic study of the diverse Frankish- and Islamic-ruled societies, by shifting the focus of inquiry from the internal history of separate groups to their areas of contact; to empower local Christian communities by documenting their deep-rootedness in these complex societies, and to contribute new knowledge of the diversity of the Islamic-ruled world as a historical reality by expanding digital inclusiveness. By achieving its various objectives, ChrIs-cross will realize what arguably is an unprecedented exploration. It will thus have a major scholarly and social impact, both for the many Christian communities now facing extinction, and for people in the so-called West, which faces an inflation in essentialist discourses on religion.