During the French period (1699-1765), the Illinois country, in the upper Mississippi Valley, owed its growth to European-style commercial agriculture, based mainly on the labor of black slaves. Even though not a majority of the colony's population (in contrast to Lower Louisiana), slaves formed a large group. This article compares Upper and Lower Louisiana to distinguish the particularities of the Illinois slave system. At the same time, it discusses historians' divergent views on slavery and on African-European relations in Lower Louisiana. The comparison demonstrates that Africans and Afro-Creoles experienced better conditions of life in Illinois, but enjoyed less economic and cultural autonomy than their counterparts in Lower Louisiana. Within the context of a hierarchical and inegalitarian European society, relations between Africans and Europeans in Illinois varied by social group, but were never entirely free of racism.