Mission San Juan Capistrano was a Spanish mission in colonial Las Californias. Its ruins are located in present-day San Juan Capistrano, Orange County, southern California.
The mission was founded on All Saints' Day November 1, 1776, by Spanish Catholics of the Franciscan Order. Named for Giovanni da Capistrano, a 15th-century theologian and "warrior priest" who resided in the Abruzzo region of Italy, San Juan Capistrano has the distinction of being home to the oldest building in California still in use, a chapel built in 1782. Known alternately as "Serra's Chapel" and "Father Serra's Church," it is the only extant structure where it has been documented that the padre Junipero Serra celebrated mass. One of the best known of the Alta California missions, and one of the few missions to have actually been founded twice-others being Mission San Gabriel Arcángel and Mission La Purísima Concepción. The site was originally consecrated on October 30, 1775, by Father Fermín Lasuén, but was quickly abandoned due to unrest among the indigenous population in San Diego.
The success of the settlement's population is evident in its historical records. Prior to the arrival of the missionaries, some 550 indigenous Acjachemen peoples lived in this area of their homeland. By 1790, the number of Indian reductions had grown to 700 Mission Indians, and just six years later nearly 1,000 "neophytes" (recent converts) lived in or around the Mission compound. 1,649 baptisms were conducted that year alone, out of the total 4,639 people converted between 1776 and 1847.