The Calmecac ("the house of the lineage", [kalˈmekak]) was a school for the sons of Aztec nobility (pīpiltin [piːˈpiɬtin]) in the Late Postclassic period of Mesoamerican history, where they would receive rigorous religious and military training. The two main primary sources for information on the calmecac and telpochcalli are in Bernardino de Sahagún's Florentine Codex of the General History of the Things of New Spain (Books III, VI, and VIII) and part 3 of the Codex Mendoza. Although the calmecac has been characterized as for elites only, Sahagun's account says that at times commoners, macehualtin were assigned to the calmecac as well and trained for the priesthood. The Tēlpochcalli ([teːɬpot͡ʃˈkalːi] "house of youth") was where mostly commoners and some noble youths received military training, but would have been precluded from the higher ranks of power. Codex Mendoza's account of the calmecac emphasizes the possibilities of upward mobility for young commoner men, (macehualtin), educated in the telpochcalli. The placement of a noble youth in the telpochcalli might have been by lesser wives' or concubines' sons or younger sons, perhaps of commoner status, so that the boys did not have to compete with noble youths in the calmecac. Codex Mendoza's account largely ignores class distinctions between the two institutions.
The calmecac of the Aztec capital, Tenochtitlan, was located in the ceremonial center of the city and it was dedicated to Quetzalcoatl.
The calmecac was the students' home for the duration of their training, and they would enter the school as young as five to seven years of age. The students received instruction in songs, rituals, reading and writing, the calendar (tōnalpōhualli [toːnaɬpoːˈwalːi]) and all the basic training which was also taught in the telpochcalli.