The Diocese of Monterey in California (Latin: Dioecesis Montereyensis in California) is an ecclesiastical territory or diocese, of the Latin Church of the Catholic Church in the central coast region of California. It comprises Monterey, San Benito, San Luis Obispo and Santa Cruz counties.

The mother church of the Diocese of Monterey in California is the Cathedral of San Carlos Borromeo in Monterey. The diocese serves close to 200,000 Catholics in 46 parishes and 18 schools. It is also home to seven of California's 21 Franciscan missions, more than any other California diocese.

Since 1849, four different dioceses in California have included the Monterey name:

• Diocese of Monterey (1849 to 1859, now defunct) – covered all of central and southern California
• Diocese of Monterey-Los Angeles (1859 to 1922, now defunct) – covered all of central and southern California
• Diocese of Monterey-Fresno (1922 to 1967, now defunct) – covered the central coast and the central valley of California
• Diocese of Monterey in California (1967 to present, current diocese ) – covers the central coast of California

The history of the Catholic Church in Monterey began with the establishment of Mission San Carlos Borromeo on Monterey Bay in 1770 by Reverend Junípero Serra. Serra moved the mission to present day Carmel the next year. It would serve as the headquarters of the Spanish missions along the Alta California coast.

• Serra established the Mission San Luis Obispo de Tolosa Mission in San Luis Obispo in 1772.
• Reverend Fermín Francisco de Lasuén founded the Mission Santa Cruz in Santa Cruz and the Mission Nuestra Señora de la Soledad in Soledad in 1791.

After the end of the Mexican War of Independence, the new Mexican Government in 1835 secularized all of the still existing Catholic missions in Alta California.

In 1840, Pope Gregory XVI set up the Roman Catholic Diocese of California. The new diocese included the following Mexican territories:

• Alta California (Upper California), including the modern American states of California, Nevada, Arizona, and Utah, along with western Colorado and southwestern Wyoming
• Baja California Territory (Lower California), including the modern Mexican states of Baja California and Baja California Sur

Gregory XVI set the episcopal see at present-day San Diego in Alta California and made the Diocese of California a suffragan of the Archdiocese of Mexico City. The first bishop of the new diocese was Francisco Garcia Diego y Moreno. Moreno designated the Mission Santa Barbara in Santa Barbara as his pro-cathedral.

After ceding Alta California to the United States at the close of the Mexican–American War in 1848, the government of Mexico objected to San Diego, a see city now located in the United States, having jurisdiction over Mexican parishes. In response, the Vatican divided the Diocese of California into American and Mexican sections in 1849. The American section became the Diocese of Monterey; the see city was moved to Monterey because of its more central location. The Royal Presidio Chapel in Monterey became the cathedral of the new American diocese.

Pope Pius IX split the Diocese of Monterey in 1853, erecting the Metropolitan Archdiocese of San Francisco. He designated the Diocese of Monterey as a suffragan diocese of the new archdiocese.

In 1859, Pius IX changed the name of the diocese to the Diocese of Monterey-Los Angeles due to the growth of the City of Los Angeles. In 1922, Pope Pius XI suppressed the Diocese of Monterey-Los Angeles, erecting in its place the Diocese of Los Angeles-San Diego and the Diocese of Monterey-Fresno.

In 1936, Pope Pius XI elevated the Diocese of Los Angeles-San Diego to the Archdiocese of Los Angeles and designated the Diocese of Monterey-Fresno as one of its suffragan sees.

In 1967, Pope Paul VI divided the Diocese of Monterey-Fresno into the Diocese of Fresno and the Diocese of Monterey in California. The pope named Auxiliary Bishop Harry Anselm Clinch of Monterey-Fresno in 1967 as the first bishop of Monterey in California. During his 14-year tenure, Clinch implemented the reforms of the Second Vatican Council, ordained 22 priests, and established five new parishes. Clinch resigned in 1982.

The second bishop of Monterey in California was Auxiliary Bishop Thaddeus Anthony Shubsda of Los Angeles, appointed by Pope John Paul II in 1982. Shubsda was widely regarded as an expert on labor issues and social justice, and earned a reputation as an outspoken advocate of farm and factory workers in the diocese. He acted as a mediator in the Watsonville frozen food strikes. Shubsda spoke out forcefully for better living conditions for field workers, some of whom were living in caves in Salinas. His actions prompted labor leader César Chávez to remark, "The church has many flaws, but in many ways it is still the best friend we have." Shubsda hosted John Paul II's visit to the Monterey Peninsula in 1987, and actively promoted the beatification of Junípero Serra.

After Shubsda died in 1991, John Paul II named Auxiliary Bishop Sylvester Donovan Ryan of Los Angeles as the next bishop of Monterey that same year. Ryan retired in 2006. He was succeeded by Auxiliary Bishop Richard John Garcia of the Diocese of Sacramento, named by Pope Benedict XVI in 2006. Richard Garcia resigned due to Alzheimer's disease in 2018.

Pope Francis in 2018 appointed Auxiliary Bishop Daniel E. Garcia (no relation to the previous bishop) of the Diocese of Austin as the next bishop of Monterey. As of 2023, Daniel Garcia is the bishop of Monterey.

Reverend Gregory Kareta was charged in February 2003 with two counts of child molestation. The accuser said that Kareta, then serving at St. Paul the Apostle Catholic Church in Pismo Beach, molested him as an 11-year-old altar boy in the summers of 1972 and 1973. The victim said that he reported the abuse to a bishop in the Archdiocese of Los Angeles in 1985, but was encouraged to remain silent about it. The charges were dismissed in July 2003 due to the statute of limitations.

The diocese was sued in March 2003 by a San Luis Obispo man who claimed to have been sexually assaulted in the early 1970s by Reverend Orlando Battagliola. The plaintiff said that Battagliola abused him during car rides when he was a ninth grader. Battagliola was murdered in 1977 in San Francisco, possibly by a male escort.

In April 2009, Reverend Antonio Cortes of St. Mary of the Nativity Catholic Church in Salinas was arrested on charges of unlawful sexual behavior with a minor and providing alcohol to a minor. His accuser was Chris Lavorato, who said he was 16 years old when Cortes assaulted him. Cortes was convicted in March 2012 of felony charges of sodomy involving a minor and possession of child pornography and sentenced to one year in prison. After his release from prison, Cortes fled to Mexico. Lavorato sued the diocese in 2018, which settled the lawsuit that same year.

The diocese paid a $1.2 million settlement in June 2009 to a man from Yuma, Arizona, who had been sexually assaulted by two priests in Salinas when he was a child.

• The first priest was Reverend Juan Guillen, who the victim said raped him multiple times when he was an altar boy between age eight and 15. The crimes happened both in Arizona and in Salinas. Guilen was sentenced to ten years in prison in Arizona in 2003.
• The second priest was Reverend John Velez, a visiting priest from Mexico, who assaulted the victim in the rectory bedroom in Salinas multiple times in 1991. According to the diocese, officials expelled Velez from the diocese in 1991 and representatives of his order escorted him back to Mexico.

The Diocese of Monterey published a list in January 2019 of 30 clerics with credible accusations of sexual abuse.

1. Harry Anselm Clinch (1967–1982)
2. Thaddeus Anthony Shubsda (1982–1991)
3. Sylvester Donovan Ryan (1992–2006)
4. Richard John Garcia (2007–2018)
   - Gerald Eugene Wilkerson, Auxiliary Bishop of Los Angeles (apostolic administrator 2018–2019)
5. Daniel E. Garcia (2019–present)

Tod David Brown, appointed Bishop of Boise City in 1988

The Diocese of Monterey is home to the Cathedral of San Carlos in Monterey, the oldest stone building and the first cathedral in California. The other former Spanish missions in the diocese include:

• Mission San Carlos Borromeo de Carmelo – Carmel Valley
• Mission Nuestra Señora de la Soledad – Soledad
• Mission San Antonio de Padua – Jolon
• Mission San Juan Bautista – San Juan Bautista
• Mission San Luis Obispo de Tolosa – San Luis Obispo
• Mission San Miguel Arcangel – San Miguel
• Mission Santa Cruz – Santa Cruz

• Mission College Preparatory High School – San Luis Obispo
• Notre Dame High School – Salinas
• Palma High School, Salinas
• Santa Catalina School – Monterey
• Saint Francis Central Coast Catholic High School – Watsonville

• Catholic Church by country
• Catholic Church hierarchy
• List of the Catholic dioceses of the United States
• Roman Catholic Diocese of California

• History article from the Diocese's website
• Catholic Schools of the Monterey Diocese Archived 2014-08-31 at the Wayback Machine
• Catholic-Hierarchy.Org datasheet

• Diocese of Monterey Official Site
• Cathedral of San Carlos Borromeo website

36°36′00″N 121°54′00″W / 36.6000°N 121.9000°W / 36.6000; -121.9000