The vast area of Texas was originally under the spiritual jurisdiction of dioceses in Mexico, though Franciscans were the predominant clergy. Catholic evangelization of the San Antonio area started with missions San Antonio de Valero (1718), San José y San Miguel de Aguayo (1720), Nuestra Señora de la Purísima Concepción de Acuña (1731), San Juan Capistrano (1731), and San Francisco de la Espada (1731), and San Fernando parish (1731). In 1839 Rome established the Prefecture Apostolic of Texas, a missionary domain comprising the new Republic of Texas under the leadership of a prefect apostolic. Between 1838 and 1848 the number of Irish and German Catholic immigrants increased. The annexation of Texas to the United States in 1845 and the growth in the number of Catholics led to the foundation of the Diocese of Galveston (1847), which covered all of Texas, with Jean Marie Odin as bishop. The entire area between the Nueces River and the Rio Grande was soon added to Odin's diocese as a result of the Mexican War in 1846–47. With continuing immigration into Texas, including Czechs and Poles, it became necessary to divide Texas into more dioceses. Rome, acting upon a petition from the American Catholic hierarchy, established the Diocese of San Antonio in 1874. The new diocese included the territory between the Colorado and the Nueces rivers and westward to the Big Bend country. The first bishop was Anthony Dominic Pellicer of Mobile, Alabama. The parishes in the city of San Antonio itself at that time were San Fernando (1731) for the Spanish speaking, St. Mary's (1856) for the Irish, St. Michael's (1866) for the Polish community, and St. Joseph's (1868) for Germans. After San Antonio, the city of Victoria was the strongest center of Catholicism in the diocese. Martin De León built Our Lady of Guadalupe Church there in 1824. The foundation of Sacred Heart Parish in Hallettsville resulted from a missionary effort of St. Mary's in 1841. In the entire diocese lived 40,000 Catholics, served by thirty-five priests in forty churches, seven chapels, and forty-four missions.
When the Ursuline Sisters arrived in San Antonio (1851) from France by way of New Orleans and Galveston, they opened the first Catholic school in San Antonio. The Sisters of the Incarnate Word and Blessed Sacrament established the Nazareth Convent and opened Nazareth Academy in Victoria (1866). Five years before the diocese was established, the Sisters of Charity of the Incarnate Word came from Galveston to San Antonio to found Santa Rosa Infirmary (presently, Santa Rosa Medical Center). They also founded St. Joseph's Orphanage and San Fernando School (1871). Later, Incarnate Word College of San Antonio was established by the Sisters of Charity of the Incarnate Word (1881). The Sisters of Divine Providence came to Texas from France (1866). Their initial foundation was in Austin, but two years later they staffed a school at Castroville. They selected San Antonio as the site of Our Lady of the Lake College (1896). The Sisters of the Holy Spirit and Mary Immaculate founded a convent in San Antonio to work among African Americans. They served at St. Peter Claver (founded 1888), the oldest black church in the diocese, and later staffed St. Peter Claver Academy and Healy-Murphy Center. After arriving from Bordeaux, France, in 1852, four members of the Society of Mary, a religious order of teaching priests and brothers called Marianists, established St. Mary's Institute. The Institute became Central Catholic High School. The Marianists founded St. Louis College (1893), which is presently known as St. Mary's University. In 1884 the Oblates of Mary Immaculate, a religious community of priests and brothers, first staffed the present St. Mary's Church, San Antonio, and Our Lady of Refuge in Eagle Pass (1884). With the growth in the number of Catholics, the Oblates staffed an increased number of churches, while conducting missions ("revivals") and retreats. The Oblates founded San Antonio Theological and Philosophical Seminary (1903), which was quickly followed by the establishment of the Province of the Oblates of the Southwest. With headquarters in San Antonio, it became the second American Oblate province. A new theological seminary called De Mazenod Scholasticate, established in 1927, became the Oblate School of Theology.
Rome altered the boundaries of the diocese by transferring certain counties west of the Nueces River into the diocese and certain counties north of the Nueces into the Vicariate of Brownsville (1877); land west of the Pecos went to the Diocese of El Paso (1914). Even so, the Diocese of San Antonio remained large, and pressure to serve the growing number of Catholics increased. San Fernando Cathedral was rebuilt under the direction of Bishop Pellicer (1880). John C. Neraz was consecrated bishop of San Antonio there in 1881. When he took office, 47,000 Catholics resided in the diocese, where fifty parishes and eight chapels were served by thirty-eight priests. The diocese was subsequently divided into local organizations: the Seguin Deanery, the Floresville Deanery, the Pleasanton Deanery, the Fredericksburg Deanery, the Del Rio Deanery, the Uvalde Deanery, and the Hondo Deanery. The Diocese of San Antonio became an archdiocese in 1926. Arthur Jerome Drossaerts, appointed ordinary in 1918, became archbishop. By the 1930s the Catholic population had reached 195,000. Both Drossaerts and his predecessor, John W. Shaw, offered refuge to numerous clerics fleeing the turmoil of the Mexican Revolution (1910–21). Major attention was given the San Antonio missions when San José was repaired, and the missions were staffed with Franciscan and Redemptorist priests. The archdiocese played a significant role in the bicentennial celebrations of the founding of San Antonio (1931). During the Texas Centennial (1936), the supposed remains of the Alamo defenders were placed in a marble sarcophagus at the cathedral. The archdiocese was lifted beyond its missionary stages with the leadership of Robert E. Lucey, who became archbishop in 1941. Within months Lucey had organized a Catholic Welfare Bureau, a Catholic Action Office, and an Archdiocesan Council of Catholic Men. He improved the faculty of St. John's Seminary and sponsored seminars on social justice for the clergy and the laity. San José Mission was made a National Historical Site (1941). The archdiocese increased expenditure of funds to preserve the other missions. The Confraternity of Christian Doctrine was established to promote Christian education, and the first official archdiocesan newspaper, the Alamo Register, was founded (1942). When the Bishops' Committee for the Spanish Speaking (later the Bishops' Committee for Hispanic Affairs) was organized by the bishops of the Southwest (1945), the archbishop of San Antonio was appointed executive chairman. Seminary facilities were enlarged with new construction at St. John's Junior Seminary (1947) and the foundation of Assumption Seminary (1951). The Catholic population had reached about 500,000 when Monsignor Stephen A. Leven was made Lucey's auxiliary bishop in 1956. All schools in the archdiocese were integrated a year before the 1954 Supreme Court ruling against segregation in public schools. Under Lucey's administration about 400 building projects were completed in the archdiocese.
Francis J. Furey succeeded Lucey as archbishop in 1969. The archdiocese benefited from his leadership when he consolidated all debts under a monthly amortization plan. The Commission for Mexican American Affairs was established in 1970. Patrick F. Flores, was named auxiliary to the archbishop (1970), thus becoming the first Hispanic member of the hierarchy in the United States. The archdiocese promoted a movement to honor "loyal and devoted laity" by conferring a bronze medal and a certificate of award to 1,040 men and women (1972–73). The Mexican American Cultural Center was founded on the grounds of Assumption Seminary (1973) as national headquarters for research, education, and leadership formation in the pastoral care of the Hispanic American community. The Alamo Messenger was renamed Today's Catholic. Progress during Furey's tenure included the establishment of eleven new parishes. When Furey died (1979), Patrick F. Flores was installed as the eighth ordinary and fourth archbishop of the archdiocese. In 1983 the four Spanish colonial missions of the archdiocese became the San Antonio Missions National Historical Park. In January 1983 ground was broken for a new chancery office for archdiocesan administrative offices. An archdiocesan fund campaign, Reflections '83, provided support for education, welfare, the care of the elderly, and preservation of the Spanish mission churches. The Diocese of Victoria, established in 1982, included all of the archdiocese east of Gonzales and Karnes counties. Monsignor Bernard F. Popp was consecrated auxiliary bishop (1983) to assist the archbishop. By 1996 there were 642,824 Catholics in 145 parishes in the archdiocese, who were served by 435 priests, 1,025 nuns, 106 brothers, and 230 permanent deacons. The major religious event of the 1980s was the visit of Pope John Paul II to San Antonio on September 13, 1987. See also CATHOLIC CHURCH.