From the mid-eleventh to the early seventeenth century (if one accepts the Moriscos as a Muslim population), significant populations of subject Muslims thrived or survived under Christian rule in the Medieval Mediterranean. In some regions (e.g. Sicily) they were expelled quite early (early 1200s), whereas in others (notably the Crowns of Aragon and Castile) they persevered beyond the end of the Middle Ages. The present paper examines the fates of the various subject Muslim communities around the Latin Mediterranean with the aim of sketching out a model that accounts for the fact that some communities were remarkably durable and others fatally vulnerable. Clearly, neither the notion of a general decline of “tolerance” in Christian society nor the development of a “persecuting society” can account for this, given that the fates of local communities varied widely, that there was not a general trend towards marginalization and expulsion, and because the various communities (together with Jewish communities) suffered repression or enjoyed integration according to distinct time-scales. Based on a tremendous amount of primary and secondary research (the basis of the first [forthcoming] scholarly monograph that surveys subject Muslim communities of Latin Christendom as a whole, this paper proposes a dynamic of “Convenience” (conveniencia to Americo Castro’s convivencia) to account for their varying experiences. This is to say, the status of subject Muslim communities was established by bilateral agreement at the time of their surrender, and subsequently came to be enshrined on the law of Christian principalities. Inevitably political and economic integration or engagement between subject Muslims and various factions, institutions and individuals among the ruling Christian elite and common people developed. This led to relationships of co-dependency between Muslims and Christians, and it was this element of symbiosis (at times coercive, and enforced violently) which set the conditions for the survival of these communities on both the “national” and local scales. It is a model that is data-driven, and eschews wooly and value-laden argument based on supposed notions of “tolerance” or of idealizations of either Islamic or Christian society and culture. As such it will contribute to moving the debate on the nature of the interaction of ethno-religious communities beyond its current historiographical and ideological swamp it has become mired in over the last decades.