From the Mission San Juan Capistrano website:

Mission San Juan Capistrano, named for St. John of Capistrano, Italy, a theologian of the 14th century, is the seventh mission founded November 1, 1776, the Feast of All Saints, by Fr. Junipero Serra. Previously established by Fr. Fermin Lasuen on October 30, 1775, it was abandoned because of Indian unrest at Mission San Diego. The Great Stone Church began construction in 1796; was completed in 1806;and was destroyed by an earthquake 1812. The Mission was secularized 1833, sold in 1845, and was returned to the Church in 1865.

Mission San Juan Capistrano was founded twice; the first attempt was In October of 1775, when Father Lasuen left San Diego with eleven soldiers to establish a mission roughly halfway between Mission San Diego and Mission San Gabriel. On October 30, 1775, a large cross was set up and Fr. Lasuen took formal possession of the land in the name of the crown and dedicated the ground. A number of Indians watched and helped to haul timber for the building of a temporary chapel and dwellings. The work went on for eight days, but came to a halt when word reached the Spaniards that Mission San Diego had suffered an Indian attack. The bells were hastily buried and the small party hurried south to take shelter in the Mission at San Diego.

After a year's delay, an expedition led by Father Junipero Serra, arrived at the same site on October 31, 1776, with two padres and an escort of soldiers. The following day, November 1, 1776, the mission was officially dedicated

Once established, the mission prospered almost from the start. Between the founding and 1797, a number of adobe buildings were erected. In 1777, the first little church was built, a modest structure that is still in use today. Considered the oldest church in California, it is called "Serra Chapel" because it is the only building still standing where Fr. Serra had celebrated Mass.

Links:

Mission San Juan Capistrano

Mission Basilica San Juan Capistrano