During the nineteenth and twentieth centuries, in the region stretching from Morocco to Iran, Muslims, Christians, and Jews inhabited shared worlds. They held in common daily experiences, attitudes, and languages, and rubbed shoulders in villages, city neighborhoods, and apartment buildings. Because Muslims, Christians, and Jews shared so much of everyday existence, one can and should study them together, even while recognizing how fluctuating social tensions and power differentials strained their mutual relations. This research into the history of inter-communal relations considers the overlapping and ever-evolving varieties of Muslim, Christian, and Jewish cultures in the modern Middle East. By identifying a mostly stable, mostly peaceful, and culturally pluralistic past, its reading of history offers hope for shared futures, particularly in Western countries where Muslim communities are growing today.