This paper traces the significant role of Sufism in promoting Muslim—Christian dialogue at a time of growing friction and colonial encroachment. The widening gap in power and wealth between the Western and Muslim world from the 19th century onward heightened cultural animosity between the two but also evoked ecumenical efforts to diffuse this contention. One such effort was Islamic modernism, which promoted a liberal interpretation of scripture and advocated the establishment of an inclusive polity that would encompass women and religious minorities. Islamic modernism gained considerable attention in the research literature. By contrast, another important ecumenical discourse, based on Sufism, which emerged in the early 20th century and was joined by Muslims and European Christians alike, has remained largely unexplored in the literature. Cairo, Rome, and Paris constituted the geographical points of convergence of this discourse; the Sufi teachings of Ibn al-ءArabi (d. 1240) provided its ideological core. Most participants sought to position Sufi values as a cultural bridge between East and West, although political considerations were also involved. This paper shows that far from being anachronistic or detached from reality, as some of its vociferous critics charged, Sufism remained a vital tradition well into modern times. Moreover, it engendered a lively debate within Western intellectual circles over the role of spirituality in modern life.