Nahuatl was the indigenous, prehispanic Mexican language, still spoken today, and related to the nontonal languages of Mesoamerica. Several Nahuatl dialects are mentioned: Cazcan, Pipil, the extinct Pochuteco, and four dialects distinguished geographically, east, north, central, and west. These are discussed with attention to the development of Nahuatl. (Text is in Spanish.) (CK)