What was the language spoken in mission San Juan Capistrano?

The language spoken at Mission San Juan Capistrano was Acjachemen, also known as Juaneño. Acjachemen is an Uto-Aztecan language that was spoken by the indigenous peoples of the area, the Acjachemen people. The language was also spoken at the nearby missions of San Luis Rey de Francia and San Gabriel Arcángel. Acjachemen is now considered to be an extinct language, as there are no known native speakers remaining.