Vocabulario en lengua castellana y mexicana is a bilingual dictionary of Spanish and Nahuatl by Alonso de Molina, first published in 1555 originally entitled Aquí comiença un vocabulario en la lengua castellana y mexicana, edited by Juan Pablos.

The Franciscan missionaries promoted the writing of literature works to evangelize the Indians in their own language, Nahuatl being one of the most important considering that it was spoken throughout New Spain.

[1] During the rule of viceroy Martín Enríquez de Almanza, Molina published Spanish-to-Nahuatl and Nahuatl-to-Spanish vocabularies to help the formation of priests that were to accomplish the evangelizing assignments.

[2] Molina's Vocabulario is considered the most important dictionary of the Classical Nahuatl language and has continued to be reprinted into the 20th century.

At the end of the first section there is an attachment, which already appeared in the 1555 edition, where the Franciscan gives grammatical instructions of the numbers in Nahuatl, with equivalences in Spanish.