The Diocese of Kansas City–Saint Joseph (Latin: Dioecesis Kansanopolitanae–Sancti Josephi) is a Latin Church ecclesiastical territory, or diocese, of the Catholic Church in northwestern Missouri in the United States. It is a suffragan diocese in the ecclesiastical province of the metropolitan Archdiocese of Saint Louis.

The mother church of the diocese is the Cathedral of the Immaculate Conception in Kansas City. Its co-cathedral is the Cathedral of St. Joseph in St. Joseph. As of 2023, the bishop is James Vann Johnston, Jr.

The Diocese of Kansas City-Saint Joseph encompasses the following counties:

Andrew, Atchison, Bates, Buchanan, Caldwell, Carroll, Cass, Clay, Clinton, Daviess, DeKalb, Gentry, Grundy, Harrison, Henry, Holt, Jackson, Johnson, Lafayette, Livingston, Mercer, Nodaway, Platte, Ray, St. Clair, Vernon and Worth.

The first Catholic presence in Missouri was that of European explorers in the 17th century traveling the Mississippi River. In present-day Hannibal, Missouri, the first Catholic masses were celebrated by the Belgian missionary, Reverend Louis Hennepin, in 1680 at Bay de Charles. At that time, all of Missouri was part of the French colony of Louisiana. Up until the early 19th century, Catholics in this region were first under the French jurisdiction of the Diocese of Quebec, then Spanish jurisdiction under the Diocese of Louisiana and the Two Floridas.

The first Catholic chapel in Western Missouri was established at Chocteau's Bluff near present-day Kansas City, Missouri.

With the Louisiana Purchase of 1804, Missouri passed from France to the United States and the bishop of the Diocese of New Orleans assumed jurisdiction for Catholics in Missouri. In 1826, Pope Leo XII erected the Diocese of St. Louis, covering the new state of Missouri along with vast areas of the American Great Plains. The northwestern Missouri region would remain part of this diocese for the next 57 years.

The first parish in the present-day diocese was St. Mary's, founded in Independence in 1823 to serve French-Canadian families in the area. In the Kansas City area, the first Catholic church was dedicated in 1833. Immaculate Conception Church in Kansas City was completed in 1857.

On September 10, 1880, Pope Leo XIII established the Diocese of Kansas City, with territories taken from the Archdiocese of St. Louis. The pope named Bishop John Joseph Hogan from the Diocese of St. Joseph as the first bishop of Kansas City. The Jesuit Order opened Rockhurst College in Kansas City in 1910. In 1919, Bishop Thomas Francis Lillis from the Diocese of Leavenworth was named by Pope Pius X as coadjutor bishop to assist Hogan.

When Hogan died in 1913 after 33 years as bishop, Lillis automatically succeeded him. Lillis delivered the invocation at the second session of the 1928 Republican National Convention in Kansas City. In 1933, Lillis drafted a resolution signed by many of his fellow Catholic bishops and 350 priests in an effort to end lynchings of African-Americans. Lillis died in 1938.

The next bishop of Kansas City was Bishop Edwin Vincent O'Hara of the Diocese of Great Falls, named by Pope Pius XII in 1939. Within his first ten years as bishop, O'Hara built or purchased 42 churches, 31 rectories, 24 colleges, high schools, and grade schools, 14 convents, eight social centers, and six hospitals. Of the 30 churches he constructed in rural areas, 25 were their first Catholic church in the county.

A proponent of Catholic Action, O'Hara encouraged lay involvement in the diocesan administration and appointed laypeople to several top diocesan positions. He obtained approval from the Vatican to use English in parts of the mass and the administration of sacraments. O'Hara founded Queen of the World Hospital in Kansas, the first racially integrated hospital in the diocese and then integrated the other Catholic medical centers. In 1954, Pius XII named Auxiliary Bishop John Cody of St. Louis as coadjutor bishop in Kansas City-Saint Joseph to assist O'Hara.

In July 1956, Pius XII redrew the diocesan boundaries in parts of Missouri:

• The pope suppressed the Dioceses of Kansas City and Saint Joseph.
• He created the new Dioceses of Kansas City-Saint Joseph, Jefferson City and Springfield-Cape Girardeau.
• The Archdiocese of St. Louis was left unchanged.

After O'Hara died in September 1956, Cody automatically succeeded him as bishop. After a few years in the diocese, Cody in 1962 was named coadjutor archbishop of New Orleans.

The next bishop in Kansas City-Saint Joseph was Bishop Charles Herman Helmsing of Springfield-Cape Girardeau, selected by Pope John XXIII in 1962. In 1968, Helmsing condemned the National Catholic Reporter (NCR), based in Kansas City. He objected specifically to NCR's stands on artificial birth control and priestly celibacy, along with its criticism of the church hierarchy. Sixty-six Catholic journalists signed a petition supporting NCR. Helmsing retired in 1977.

Bishop John Sullivan of the Diocese of Grand Island was appointed bishop of Kansas City-Saint Joseph by Pope Paul VI in 1977. After 16 years as bishop, Sullivan retired in 1993 due to a diagnosis of Parkinson's disease. Pope John Paul II then named Bishop Raymond Boland of the Diocese of Birmingham to replace Sullivan. In 2004, Reverend Robert Finn of St. Louis was named by John Paul II as coadjutor bishop of the diocese. When Boland retired in 2005, Finn automatically became the next bishop of Kansas City-Saint Joseph.

Upon becoming bishop, Finn said that vocations to the priesthood and religious life would be seen as a "super-priority" for his diocese. Before Finn's arrival, in 2003, the diocese reported having nine seminarians. By 2007, the diocese reported 24 men studying for diocesan priesthood.

In September 2014, Pope Francis ordered an investigation into Finn's tenure as bishop, to be conducted by Canadian Archbishop Terrence Prendergast. Cardinal Seán Patrick O'Malley, the leader of a church commission on child abuse cases, said in an interview that Finn's misdemeanor conviction for failure to report child abuse would have disqualified him from teaching Sunday school in the Archdiocese of Boston. "It's a question that the Holy See needs to address urgently," O'Malley said. In 2015, Finn resigned as bishop of Kansas City-Saint Joseph.

The current bishop of the Diocese of Kansas City-St. Joseph is Bishop James Vann Johnston Jr. from Springfield-Cape Girardeau. He was appointed by Pope Francis in 2015.

In 2022, Johnston demanded that Martin Navarro, a self-styled religious brother, stop wearing a habit, cease fundraising in the diocese and stop building an unauthorized chapel. Navarro, who refused Johnston's orders, had found the Oblates of St. Augustine religious institute in the diocese. Johnston had refused permission for its founding.

In 2004, Bishop Emeritus Joseph Hubert Hart of the Diocese of Cheyenne was named in a civil lawsuit alleging that he sexually abused three children while serving as a priest in the Diocese of Kansas City-Saint Joseph and in Cheyenne. Hart had allegedly been transferred to Cheyenne in the 1970s after sex abuse allegations surfaced against him in Missouri. In 2005, a fifth person alleged abuse by Hart in 1973 or 1974, when the man was a 12-year-old parishioner at St. John Francis Regis Parish. In 2008, the diocese made a $10 million settlement with the accusers. As part of the settlement, Bishop Finn agreed to report any future suspected abuse to law enforcement.

In May 2011, Bishop Finn apologized to the diocese for his failure to act in the case of Reverend Shawn Ratigan. In May 2010, an elementary school principal sent Flynn a letter reporting numerous examples of inappropriate behavior by Ratigan towards children; however, Flynn never read it. In December 2010, a technician discovered inappropriate images of children on Ratigan's computer and notified diocesan officials. Monsignor Murphy, the vicar general, described one graphic image by telephone to a police officer, who gave his personal opinion that the image did not meet the Missouri standard for child pornography. The vicar general notified Finn of the conversation, who did not pursue it further. Before Finn could confront Ratigan, the priest attempted suicide. Finn then sent Ratigan to a psychiatric facility. Several months later, Murphy asked police to investigate Ratigan. In May 2011, police searched Ratigan's home and found child pornography. He was arrested a week later on child pornography charges.

In June 2011, Finn appointed former U.S. Attorney Todd P. Graves to investigate diocesan policies and procedures on sexual misconduct by clergy. Finn also announced the appointment of an independent public liaison and ombudsman. In September 2011, Graves released his report, saying that "diocesan leaders failed to follow their own policies and procedures for responding to reports" of sexual abuse by clergy.

In October 2011, a grand jury indicted both the diocese and Finn for failing to report suspected child abuse, a criminal misdemeanor. The indictment charged Finn with failing to inform police about child pornography in the Ratigan case. Finn was convicted on one charge in September 2012 and sentenced to two years of probation. All charges against the diocese itself were dropped. Ratigan was convicted of producing child pornography in 2013 and was sentenced to 50 years in prison. In June 2014, the diocese was ordered by a court arbitrator to pay an additional $1 million to sexual abuse survivors because the diocese had broken the promise it made in the 2008 settlement when it failed to report the suspected abuse by Ratigan.

The diocese in 2019 released a list of 19 clergy with credible accusations of sexual abuse of minors. In August 2019, Reverend Benedict Neenan, abbot of Conception Abbey, released a list of eight monks who were credibly accused of committing acts of sex abuse while serving in the diocese. Neenan also issued an "unconditional apology to all victims and their families affected by the evil of clergy sexual abuse."

By August 2019, Hart was facing over 12 sex abuse accusations from both Kansas City–Saint Joseph and Cheyenne. Reports surfaced that during the 1970s, Monsignor Thomas O’Brien and Hart allegedly used a house owned by O'Brien on Lake Viking in Missouri to sexually abuse children. Shortly before his death in 2013, O'Brien had agreed to pay a wrongful death settlement of over $2 million to the family of one victim who committed suicide. In January 2021, the Congregation for the Doctrine of the Faith in the Vatican cleared Hart of seven sexual abuse charges and stated that five other charges could not be proven. Later that month, Wyoming Attorney General Bridget Hill announced that her office would not pursue criminal charges against Hart.

In July 2020, two new lawsuits were filed in Jackson County Circuit Court against the diocese, involving alleged rape by two priests in 2018. The lawsuit alleges that the diocese covered up the abuse, which then allowed the two priests to gain access to and sexually abuse other vulnerable individuals as well. One of the two accused priests, now dead, was on the diocese's 2019 list. The other, who was not on the accused list, was revealed to have been placed on leave from his duties in 2018.

In March 2021, Bishop Johnston announced the laicization in December 2020 of Michael Tierney, a former diocesan priest. Tierney had faced multiple credible accusations of sexual abuse of children.

In September 2020, just before the 2020 US presidential election, Johnston sent a controversial letter to parishioners in the diocese. In the letter, Johnston asked voters to examine which party supported so-called moral issues such as abortion rights. When asked if Johnston was endorsing Republican Party candidates, he said that he was only asking voters to vote their conscience.

See Diocese of Saint Joseph for a list of its bishops.

1. John Joseph Hogan (1880–1913)
   - John J. Glennon (coadjutor bishop 1896–1903); appointed Coadjutor Archbishop of St. Louis before succession and subsequently succeeded to that see (elevated to Cardinal in 1946)
2. Thomas Francis Lillis (1913–1938)
3. Edwin Vincent O'Hara (1939–1956), elevated to Archbishop (ad personam) in 1954

1. John Patrick Cody (1956–1961; coadjutor Bishop of Kansas City 1954–1956), appointed Coadjutor Archbishop of New Orleans, subsequently succeeding to that see, and later Archbishop of Chicago (elevated to Cardinal in 1967)
2. Charles Herman Helmsing (1962–1977)
3. John J. Sullivan (1977–1993)
4. Raymond James Boland (1993–2005)
5. Robert W. Finn (2005–2015; coadjutor bishop 2004–2005)
   - Joseph Fred Naumann, apostolic administrator (2015).
6. James Vann Johnston, Jr. (2015–present)

• Joseph M. Marling (1947–1956), appointed Bishop of Jefferson City
• Joseph Vincent Sullivan (1967–1974), appointed Bishop of Baton Rouge
• George Kinzie Fitzsimons (1975–1984), appointed Bishop of Salina

• Michael Francis McAuliffe, appointed Bishop of Jefferson City in 1969
• William Wakefield Baum, appointed Bishop of Springfield-Cape Girardeau in 1970 and later Archbishop of Washington, Prefect of the Congregation for Catholic Education, and Major Penitentiary of the Apostolic Penitentiary (created a Cardinal in 1976)
• Joseph Hubert Hart, appointed Auxiliary Bishop (in 1976) and later Bishop of Cheyenne in 1978
• Lawrence James McNamara, appointed Bishop of Grand Island in 1978

The Diocese of Kansas City-Saint Joseph has seven high schools and 24 elementary schools or pre-schools.

School	Location	Oversight	Opened
Bishop LeBlond High School	St. Joseph	Run by diocese	1960
Cristo Rey Kansas City High School	Kansas City	Cristo Rey Network and Sisters of Charity of Leavenworth	2006
Notre Dame de Sion School	Kansas City	Sisters of Notre Dame de Sion	1912
Rockhurst High School	Kansas City	Society of Jesus	1910
St. Michael the Archangel Catholic High School	Lee's Summit	Run by diocese	2017
St. Pius X Catholic High School	Kansas City	Run by diocese	1956
St. Teresa's Academy	Kansas City	Sisters of St. Joseph of Carondelet	1866

School	Location	Oversight	Opened	Closed
Archbishop O'Hara High School	Kansas City	Run by diocese	1965	2017
Bishop Hogan High School	Kansas City	Run by diocese	1935	1999
St. Mary's High School	Independence	Run by diocese	1853	2013

• Roman Catholic Diocese of Kansas City–Saint Joseph Official Site
• Charism Workshop hosted by KCSJ

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