Protestantism was illegal in eighteenth-century France, yet many French Reformed Protestants, better known as Huguenots, managed to maintain their religion and identity until the French Revolution granted religious freedom. Several thousand of them lived in Paris, but remained a tiny minority in a very Catholic city. Given this context, and little access to pastors or collective worship, what kind of Protestantism did they observe? This article suggests that, like other minority groups, their religious practice and thinking were influenced both by the Catholic environment in which they lived and by the culture of the late eighteenth-century city. By 1789 they had moved away from certain Calvinist traditions, and some of them had adopted a surprising ecumenism.