Mission Santa Barbara was founded on 4 December 1786 by the Franciscan Fermín Francisco de Lasuén, near a Spanish presidio and within the homeland of Chumash peoples. It became the tenth mission in Alta California and was dedicated to Saint Barbara. The institution aimed to extend Spanish authority and convert Indigenous communities to Catholicism. Chumash labor, knowledge, and craft built and sustained the mission, while colonial rules sought to regulate residence, work, marriage, ceremony, and movement.

Several early adobe churches preceded the present structure. The mission developed farms, ranches, workshops, reservoirs, aqueducts, and mills that drew on Chumash labor and the region's resources. Population increased as people were baptized and relocated from surrounding villages, but introduced diseases caused severe mortality. The great earthquake of 1812 damaged the third church. A new stone church, begun soon afterward and dedicated in 1820, used a neoclassical façade and paired bell towers that later inspired Santa Barbara's Spanish Colonial Revival image.

Mexico secularized the missions in the 1830s, breaking up lands and removing many resources from Franciscan control. Chumash residents faced further displacement, though some remained connected to the mission and town. Unlike most California missions, Santa Barbara continued to house a Franciscan community. The buildings served as church, residence, school, archive, and later seminary. Earthquakes in 1925 and 1978 caused substantial damage, and repairs or rebuilding altered towers, roofs, interiors, and other features while retaining the complex's recognizable form.

The mission today includes the active parish church, friary, cemetery, museum rooms, gardens, and portions of the historic water system. Collections and archives preserve materials valuable to colonial and Indigenous history, although earlier interpretation often celebrated missionaries while minimizing coercion and Chumash loss. Conservation must address seismic risk, aging masonry, water, and visitor use. The title Queen of the Missions reflects the site's architectural prominence and preservation, but it can also obscure the labor and unequal power that created the institution.

Santa Barbara's importance lies in its layered continuity and in the difficult histories held within attractive architecture. The present church contains early nineteenth-century work, later repairs, replacements, and modern strengthening. Ongoing Franciscan and parish use gives the site a continuity rare among the missions, while Chumash communities maintain cultural identities that predate it. A complete history treats the mission as a colonial settlement, agricultural enterprise, sacred place, archive, reconstructed landmark, and location of Indigenous survival rather than as an isolated monument to Spanish expansion.