During French colonial rule in Louisiana, nuns from the French Company of Saint Ursula came to New Orleans, where they educated women and girls of European, Indian, and African descent, enslaved and free, in literacy, numeracy, and the Catholic faith. Although religious women had gained acceptance and authority in seventeenth-century France, the New World was less welcoming. Emily Clark explores the transformations required of the Ursulines as their distinctive female piety collided with slave society, Spanish colonial rule, and Protestant hostility.

The Ursulines gained prominence in New Orleans through the social services they provided - schooling, an orphanage, and refuge for abused and widowed women - which also allowed them a self-sustaining level of corporate wealth. Clark traces the conflicts the Ursulines encountered through Spanish colonial rule (1767-1803) and after the Louisiana Purchase, as Protestants poured into Louisiana and were dismayed to find a powerful community of self-supporting women and a church congregation dominated by African Americans. The unmarried nuns contravened both the patriarchal order of the slaveholding American South and the Protestant construction of femininity that supported it. By incorporating their story into the history of early America, Masterless Mistresses exposes the limits of the republican model of national unity.