This dissertation examines an early modern slave trade that extended from the Central Sahel into the Mediterranean in order to reposition Sicily’s dynamic role in defining ideas of race through its practices of slavery. From the late fifteenth century through the end of the sixteenth century, there were many enslaved Black Africans in Palermo, yet, scholarship on slavery in Sicily rarely focuses specifically on this population. More recently Sicily has been incorporated into studies of slavery on the Iberian Peninsula, as an export market of the wider Atlantic-European slave trades growing at the same time, or as an important source for captives from corsair warfare. I focus on Palermo as a Christian Mediterranean port city that became a major purchaser of enslaved West Africans from the Libyan coastline for the span of about one hundred years. First, I consider how ideologies of race were developed and transformed along this trans-Saharan slave trade route from the Central Sahel into the Mediterranean and how they justified the enslavement and forced migrations of West Africans. As enslaved Black populations grew in Iberian cities, and Spain and Portugal expanded their empires across the Atlantic, religious social hierarchies were reinvented in order to fit new marginalized communities into their world. By the end of the sixteenth century, these hierarchies had assumed a broader racial significance. Secondly, I examine the distinctions emerging in Sicily within its diverse enslaved community. Here, there was a dialectic relationship between practices of slavery and the formation of racial identities; and this is most clearly seen in how Black Africans moved into slavery differently than their North African counterparts, and had less mobility once enslaved. Black Africans were more likely to stay in Sicilian households and be converted in the Catholic church at the same time that they were in kept in subjugated social statuses even once freed. Ultimately, I am arguing that a history of enslaved Black Africans in Sicily highlights the fragile and violent nature of the boundaries between the interconnected worlds of the early modern Mediterranean, boundaries that continue to restrict mobility in the sea today.