Nahuatl is a language spoken in south-central Mexico. It was the administrative language of the Aztec empire, and accordingly was of great interest to the Spanish immigrants who later inherited the administration of Mexico. The kind of Nahuatl respresented in early Colonial texts is referred to as "Classical," in contrast to Nahuatl as it has been spoken in more recent times.

Because a knowledge Nahuatl was so important to the early Spanish, it was an object of scholarly concern already by the mid-16th century. Accordingly we have a long record of it, and in some ways this makes it one of the most interesting of the indigenous American languages to study. Indeed Nahuatl can become a consuming passion.