Among the nations of the New World, Mexico is probably the country in which the Franciscans worked most intensively. Having been the first missionaries to arrive in Mexico, they covered most of its territory and worked with numerous native groups: Nahuas, Otomies, Mazahuas, Huastecas, Totonacas, Tarascans, Mayas. Their intense missionary activity is evident in the many indigenous languages the Franciscans learned, the grammars and vocabularies they wrote, the numerous Biblical texts they translated, and the catechisms they wrote with ideographical techniques quite alien to the European mind. This activity left an indelible mark in Mexico, a mark still alive in popular traditions, monumental constructions, popular devotions, and folk art. Without a doubt, in spite of the continuous growth of the Spanish and Mestizo populations during colonial times, the favorite concern of Franciscan pastoral activity was the indigenous population. Thus, Franciscan schools and colleges, hospitals, and publications were addressed to it. For their part, the native population showed the same preference for the Franciscans. To the eyes of the civil and ecclesiastical authorities, Franciscans and natives appeared as an inseparable body, an association not always welcomed by the Spanish Crown. In fact, since the middle of the sixteenth century bishops and royal officials tried to separate them, assigning secular priests in the native towns and limiting the ecclesiastical authority of the friars.