The Archdiocese of Los Angeles (Latin: Archidiœcesis Angelorum in California, Spanish: Arquidiócesis de Los Ángeles) is an ecclesiastical territory or archdiocese of the Catholic Church (particularly the Roman Catholic or Latin Church) located in the southern portion of the U.S. state of California. The archdiocese’s cathedra is in Los Angeles, the archdiocese comprises the California counties of Los Angeles, Santa Barbara and Ventura. The cathedral is the Cathedral of Our Lady of the Angels in Los Angeles, and its present archbishop is José Horacio Gómez Velasco. With approximately five million professing members, the Archdiocese of Los Angeles is numerically the single largest diocese in the United States.
The Archbishop of Los Angeles also serves as metropolitan bishop of the suffragan dioceses within the Ecclesiastical Province of Los Angeles, which includes the dioceses of Fresno, Monterey, Orange, San Bernardino, and San Diego.
Following the establishment of the Spanish missions in California, the diocese of the Two Californias was established on 1840, when the Los Angeles region was still part of Mexico. In 1848, Mexican California was ceded to the United States, and the U.S. portion of the diocese was renamed the Diocese of Monterey. The diocese was renamed the Diocese of Monterey-Los Angeles in 1859, and the episcopal see was moved to Los Angeles upon the completion of the Cathedral of Saint Vibiana in 1876. Los Angeles split from Monterey to become the Diocese of Los Angeles-San Diego in 1922. The diocese was split again in 1936 to create the Diocese of San Diego, and the Los Angeles see was elevated to an archdiocese. The archdiocese's present territory was established in 1976, when Orange County was split off to establish the Diocese of Orange.