In the late seventeenth century, the Franciscan Order founded Franciscan Apostolic Colleges in America and Spain to train novices and friars for a missionary career and to revitalize its missionary programs in the Hispanic domains. The colleges adapted into their core teaching curriculum the conferencias or conferences, a program to instruct the clergy set by the Council of Trent (1545-1563). Conferences or ecclesiastical conferences were "meetings of clerics for the purpose of discussing, in general, matters pertaining to their state of life, and, in particular, questions of moral theology and liturgy." In the colleges, students and friars held daily meetings in the library to discuss and debate over problems and issues that concerned their evangelical ministry to the Catholics and to the non-believers. The conferencias became the crucial moment in the preparation of the missionaries at the Apostolic Colleges, where Franciscans learned Indian languages and theology and improved their rhetorical skills. This paper examines this rarely known aspect of the instruction of the missionaries who evangelized in the Spanish frontiers of North America.