The Pipiltin (sg. pilli) were the noble social class in the Mexica Empire. They are below the ruling nobles in the civilization's social structure and above the commoners who achieved noble status due to an outstanding deed in war. These people were members of the hereditary nobility and occupied positions in the government as ambassadors and ministers, the army and the priesthood. Pipiltin often headed their own noble houses, called tecalli, with their own lands and dependent labourers. The subclasses within the Pipiltin were: tlahtohcapilli (a tlahtoani's son), tecpilli or teucpilli (a teuctli's son), tlazohpilli (son of legitimate wife), and calpanpilli (son of a concubine).

Children of the Pipiltin were given extensive education in preparation for the role they will play in their adult life. They were sent to the calmecac, which was the center for higher learning, to study the ancient wisdom as well as "elegant forms of speech, ancient hymns, poems and historical accounts, religious doctrines, the calendar, astronomy, astrology, legal precepts and the art of the government."