Converting indigenous people to Christianity was a key ambition for all European powers in the New World. Galvanized by the desire to spread their religion and prevent any gains by Protestants, Catholic powers actively sponsored missionary efforts. Franciscans, Dominicans, Jesuits, and members of other religious orders who accompanied the conquistadors and subsequent settlers established Catholic missions throughout Spanish and Portuguese colonies. Later French explorers were also accompanied by missionaries who preached to the Native American tribes with whom they traded.

Rather than a straightforward imposition of Christianity, conversion entailed a complex process of cultural exchange. Catholic friars were among the first Europeans to seek understanding of native cultures and languages as part of their effort to render Christianity comprehensible to indigenous people. In addition to spreading Christianity, missionaries taught indigenous peoples European methods of agriculture and instilled loyalty to colonial masters. In turn, Christian ideas and practices in the New World took on a distinctive character. For example, a sixteenth-century apparition of the Virgin Mary in Mexico City, known as the Virgin of Guadalupe, became a central icon of Spanish-American Catholicism.

Missionaries’ success in the New World varied over time and space. In Central and South America large-scale conversion forged enduring Catholic cultures in Portuguese and Spanish colonies. Conversion efforts in seventeenth-century North America were less effective due to the scattered nature of settlement and the lesser integration of native people into the colonial community. On the whole, Protestants were less active than Catholics as missionaries, although some dissenters like Quakers and Methodists did seek converts among native people. Efforts to Christianize indigenous peoples in the New World were paralleled by missionary work by the Jesuits and other orders in the Far East.