The Diocese of Brooklyn (Latin: Diœcesis Bruklyniensis) is a Latin Church ecclesiastical territory or diocese of the Catholic Church in the U.S. state of New York. It is headquartered in Brooklyn and its territory encompasses the New York City boroughs of Brooklyn and Queens. The Diocese of Brooklyn is a suffragan diocese in the ecclesiastical province of the metropolitan Archdiocese of New York. The diocesan cathedral is the Cathedral Basilica of St. James in Downtown Brooklyn and its co-cathedral is the Co-Cathedral of St. Joseph in Prospect Heights. The current Bishop of Brooklyn is Robert J. Brennan.

Brooklyn is one of the few dioceses in the United States that is made up of 100% urban territory.

The bishop of the Diocese of Brooklyn, presides from both the Cathedral Basilica of St. James and the Co-Cathedral of St. Joseph. This atypical arrangement was required due to the small size of the Cathedral Basilica of St. James. St. Joseph's Church was designated as a co-cathedral for the Diocese of Brooklyn on February 14, 2013, by Pope Benedict XVI after Bishop Nicholas DiMarzio petitioned the Vatican.

The diocese was established in 1853 out of the territory of the Roman Catholic Archdiocese of New York, at a time when Brooklyn was still a separate city from New York City. It originally included all of Long Island, but its present-day territory was established in 1957 when Nassau and Suffolk counties were split off to form the Diocese of Rockville Centre.

The opening of the Brooklyn Navy Yard in 1801 drew a number of immigrants, largely Catholics from Northern Ireland, especially from Derry and Donegal. They would cross the East River to attend services at St. Peter's Church on Barclay Street. Periodically, John Power or others would come to celebrate Mass at the home of William Purcell or at Dempsey's Blooming Grove Garden on Fulton St. The Church of St. James was erected in 1822. In July, 1841, Johann Stephen Raffeiner, from the Tyrol, began the German parish of the Most Holy Trinity on a part of the farm of the old Dutch Meserole family in the Bushwick section. Holy Cross Cemetery was opened in 1849. In 1853, Archbishop John Hughes appointed his vicar-general, Irish-born John Loughlin, former pastor of St. Patrick's on Mulberry St. as bishop of the new diocese. Loughlin chose St. James as his cathedral.

During his episcopate, Loughlin founded 120 parishes. Plans to build the larger Cathedral of the Immaculate Conception were deferred in favor of orphanages, schools, and hospitals. He was succeeded in 1892, by Bishop Charles Edward McDonnell, former chancellor of the Roman Catholic Archdiocese of New York. The Roman Catholic Diocese of Brooklyn served at that time 250,000 Catholics. With the increase in the number of immigrants of various nationalities, McDonnell founded a number of national churches which ministered to parishioners in their own language. To this end, he invited several religious institutes into the diocese, including the Redemptorists, Benedictines, Franciscans (including the Minor Conventuals and Capuchins), Jesuits, Sisters of the Holy Family of Nazareth, Missionary Sisters of the Sacred Heart, Daughters of Wisdom, and Sisters of the Holy Infant Jesus. He also built three hospitals. Camp Wycoff and Camp Black, set up during the Spanish–American War were attended by local clergy.

Thomas Edmund Molloy was named the third Bishop of Brooklyn on November 21, 1921. In 1930 Bishop Molloy established the Seminary of the Immaculate Conception. The Roman Catholic Diocese of Rockville Centre was split off from Brooklyn April 6, 1957. Ten days later, Bryan Joseph McEntegart became the next Bishop of Brooklyn. He built six high schools, Cathedral Preparatory Seminary, and a hospital. He improved outreach to the growing Hispanic population, he sent priests and religious to study Spanish language and culture. Bishop Francis Mugavero experience as former head Brooklyn's Catholic Charities was reflected in his episcopate. In 1971, Mugavero established the Catholic Migration Office to serve the needs of immigrants and refugees living in Brooklyn and Queens. The Nehemiah project produced affordable housing in Brownsville.

In September 2018, the Roman Catholic Diocese of Brooklyn agreed to a record $27.5 million settlement for sex abuse allegations. On February 15, 2019, the Roman Catholic Diocese of Brooklyn and Queens made public a list of 108 clergy who were "credibly accused" of committing sexual abuse, some of whom have also been convicted for their crimes. Along with the list, Bishop Nicholas DiMarzio also issued a letter of apology, asking for forgiveness. In June 2020, the FBI arrested Francis Hughes, a priest serving in Queens, on child pornography charges and sex-related charges involving underage minors. In a separate case, the Vatican exonerated Bishop DiMarzio of allegations of sexual abuse dating back a half century. After an inquiry led by former FBI Director Louis Freeh, the Congregation for the Doctrine of the Faith said that the accusations were groundless.

1. John Loughlin (1853–1891)
2. Charles Edward McDonnell (1892–1921)
3. Thomas Edmund Molloy (1922–1956), elevated to Archbishop ad personam in 1951
4. Bryan Joseph McEntegart (1957–1968), elevated to Archbishop ad personam in 1966
5. Francis Mugavero (1968–1990)
6. Thomas Vose Daily (1990–2003)
7. Nicholas Anthony DiMarzio (2003–2021)
8. Robert J. Brennan (2021–present)

• James Massa (2015–present)
• Witold Mroziewski (2015–present)

• George Mundelein (1909–1915), appointed Archbishop of Chicago (Cardinal in 1924)
• Thomas Edmund Molloy (1920-1921), appointed Bishop of this diocese
• Raymond Augustine Kearney (1934–1956)
• John Joseph Boardman (1952–1977)
• Edmund Joseph Reilly (1955–1958)
• Joseph Peter Michael Denning (1959–1982)
• Charles Richard Mulrooney (1959–1981)
• John J. Snyder (1972–1979), appointed Bishop of Saint Augustine
• Joseph Michael Sullivan (1980–2005)
• René Arnold Valero (1980–2005)
• Anthony Bevilacqua (1980–1983), appointed Bishop of Pittsburgh and later Archbishop of Philadelphia (elevated to Cardinal in 1991)
• Ignatius Anthony Catanello (1994–2010)
• Gerald Barbarito (1994–1999), appointed Bishop of Palm Beach
• Guy Sansaricq (2006–2010)
• Frank Joseph Caggiano (2006-2013), appointed Bishop of Bridgeport
• Octavio Cisneros (2006–2020), retired on October 30, 2020.
• Raymond Francis Chappetto (2012–2022), retired on March 7, 2022.
• Paul Robert Sanchez (2012–2022), retired on March 30, 2022.
• Neil Edward Tiedemann (2016–2023), retired on June 30, 2023.

• George J. Caruana, appointed Bishop of Puerto Rico in 1921 and later Apostolic Nuncio and Apostolic Delegate and Titular Archbishop
• James Henry Ambrose Griffiths, appointed Auxiliary Bishop of Military, USA in 1949 and later Auxiliary Bishop of New York
• John Joseph Carberry, appointed Coadjutor Bishop (in 1956) and later Bishop of Lafayette in Indiana, Bishop of Columbus, and Archbishop of Saint Louis (elevated to Cardinal in 1969)
• Vincent John Baldwin appointed Auxiliary Bishop of Rockville Centre in 1962
• John R. McGann appointed Auxiliary Bishop of Rockville Centre in 1970 and later Bishop of Rockville Centre
• James Joseph Daly appointed Auxiliary Bishop of Rockville Centre in 1977
• Gerald Augustine John Ryan appointed Auxiliary Bishop of Rockville Centre in 1977
• Alfred John Markiewicz appointed Auxiliary Bishop of Rockville Centre in 1986 and later Bishop of Kalamazoo
• Emil Aloysius Wcela appointed Auxiliary Bishop of Rockville Centre in 1989
• Vincent DePaul Breen, appointed Bishop of Metuchen in 1997
• Edward Bernard Scharfenberger, appointed Bishop of Albany in 2014
• Kevin J. Sweeney, appointed Bishop of Paterson in 2020

• Leo Joseph White, Apostolic Prefect of Garissa, Kenya, 1976-1984 - incardinated in 1990.

The sitting bishop is also the true principal of the diocese's pre-seminary high school, Cathedral Preparatory Seminary. As of March 2009, Cathedral Preparatory Seminary is the only full-time high school seminary in the nation. Three diocesan and/or parish high schools are under the auspices of the Diocese of Brooklyn and Queens. As of 2019, only 36 Diocese of Brooklyn schools were still not scheduled to close, compared to the 102 which were operational in the 1980s. Between the mid-2000s and 2019, the Roman Catholic Diocese of Brooklyn permanently closed 45 of its schools.

• Bishop Loughlin Memorial High School – De la Salle Christian Brothers
• Cristo Rey Brooklyn High School – Cristo Rey Network
• Fontbonne Hall Academy – Sisters of St. Joseph
• Nazareth Regional High School – Xaverian Brothers
• St. Edmund Preparatory High School – Oratory of St. Philip of Neri, formerly staffed by the Dominican Sisters of Sparkill, and the Sisters of St. Joseph
• Saint Saviour High School of Brooklyn – School Sisters of Notre Dame
• Xaverian High School – Xaverian Brothers

• Archbishop Molloy High School – Briarwood, Marist Brothers
• Cathedral Preparatory School and Seminary – Elmhurst, Diocese of Brooklyn
• Christ the King Regional High School – Middle Village, Independent school, formerly staffed by the Marist Brothers and Daughters of Wisdom
• Holy Cross High School – Flushing, Congregation of the Holy Cross
• Monsignor McClancy Memorial High School – East Elmhurst, Brothers of the Sacred Heart
• St. Francis Preparatory High School – Fresh Meadows, Franciscan Brothers of Brooklyn
• St. John's Preparatory High School – Astoria, Independent school, formerly staffed by the De la Salle Christian Brothers and Sisters of Mercy
• The Mary Louis Academy – Jamaica Estates, Sisters of St. Joseph of Brentwood

There were 116 diocesan and parish elementary schools in the Roman Catholic Diocese of Brooklyn. In March 2009. In 2009, Pope John Paul II Family Academy opened at St. Barbara's School in Bushwick, In 2019, Our Lady of Guadalupe Catholic Academy in Bensonhurst and Mary Queen of Heaven Catholic Academy in Mill Basin closed, and two Bushwick schools, St Brigid and St. Frances Cabrini, merged.

• Bay Ridge Catholic Academy
• Blessed Sacrament Catholic Academy
• Brooklyn Jesuit Prep
• Good Shepherd Catholic Academy - formerly staffed by Dominican Sisters
• Midwood Catholic Academy
• Our Lady of Grace Catholic Academy
• Our Lady of Perpetual Help Catholic Academy of Brooklyn
• Our Lady of Trust Catholic Academy
• Queen of the Rosary Catholic Academy
• St. Athanasius Catholic Academy
• St. Bernadette Catholic Academy
• St. Bernard Catholic Academy
• St. Brigid-St. Frances Cabrini Catholic Academy
• St Catherine of Genoa ~ St Therese of Lisieux Catholic Academy
• St. Edmund School
• St. Ephrem Catholic Academy
• St. Francis of Assisi Catholic Academy
• St. Francis Xavier Catholic Academy - Early Childhood
• St. Gregory the Great Catholic Academy
• St. Joseph the Worker Catholic Academy
• St. Mark Catholic Academy
• St. Patrick Catholic Academy
• St. Peter Catholic Academy
• St. Saviour Catholic Academy
• St. Stanislaus Kostka Catholic Academy
• Salve Regina Catholic Academy

• Divine Wisdom Catholic Academy – Douglaston
• Holy Child Jesus Catholic Academy – Richmond Hill
• Holy Family Catholic Academy – Flushing
• Holy Trinity Catholic Academy – Whitestone
• Immaculate Conception Catholic Academy – Astoria
• Immaculate Conception Catholic Academy – Jamaica
• Incarnation Catholic Academy – Queens Village
• Notre Dame Catholic Academy – Ridgewood
• Our Lady's Catholic Academy – South Ozone Park
• Our Lady of Fatima School – Jackson Heights
• Our Lady of Grace Catholic Academy – Howard Beach
• Our Lady of Hope Catholic Academy – Middle Village
• Our Lady of Mercy Catholic Academy – Forest Hills
• Our Lady of Perpetual Help Catholic Academy – South Ozone Park
• Our Lady of Sorrows Catholic Academy – Corona
• Our Lady of the Blessed Sacrament Catholic Academy – Bayside
• Our Lady of the Snows Catholic Academy – Floral Park
• Our Lady Queen of Martyrs Catholic Academy – Forest Hills
• Resurrection-Ascension Catholic Academy – Rego Park
• Sacred Heart Catholic Academy – Bayside
• Sacred Heart Catholic Academy – Cambria Heights
• Sacred Heart Catholic Academy – Glendale
• St. Adalbert Catholic Academy – Elmhurst
• St. Andrew Avellino Catholic Academy – Flushing
• St. Bartholomew Catholic Academy – Elmhurst
• St. Clare Catholic Academy – Rosedale
• St. Elizabeth Catholic Academy – Ozone Park
• St. Francis de Sales Catholic Academy – Belle Harbor
• St. Francis of Assisi Catholic Academy – Astoria
• St. Gregory the Great Catholic Academy – Bellerose
• St. Helen Catholic Academy – Howard Beach
• St. Joan of Arc Catholic School – Jackson Heights
• St. Joseph Catholic Academy – Long Island City
• St. Kevin Catholic Academy – Flushing
• St. Leo Catholic Academy – Corona
• St. Luke Catholic School – Whitestone
• St. Margaret Catholic Academy – Middle Village
• St. Mary Gate of Heaven Catholic Academy – Ozone Park
• St. Matthias Catholic Academy – Ridgewood
• St. Mel Catholic Academy – Flushing
• St. Michael's Catholic Academy – Flushing
• St. Nicholas of Tolentine Catholic Academy – Jamaica
• St. Rose of Lima Catholic Academy – Rockaway Beach
• St. Sebastian Catholic Academy – Woodside
• St. Stanislaus Kostka Catholic Academy of Queens – Maspeth
• St. Thomas the Apostle Catholic Academy – Woodhaven
• Ss. Joachim and Anne – Queens Village

Seminary of the Immaculate Conception – Former major seminary in Huntington for the Diocese of Brooklyn, established in 1926, closed in 2012. Seminarians from the diocese now fulfill their major seminary programs at St. Joseph's Seminary in Yonkers.

Cathedral Seminary House of Formation – established in Douglaston in 1967. Currently serves as the college/minor seminary for the Archdiocese of New York, the Diocese of Brooklyn and the Diocese of Rockville Centre. Also serves as the minor seminary for students from other dioceses.

Seminarians enrolled at the Cathedral Seminary study for their undergraduate philosophy degrees at either St. John's University in Queens or Fordham University in Bronx.

The Diocese of Brooklyn has nine Catholic cemeteries serving the diocese; two in Brooklyn, five in Queens and three outside the diocese.

• Holy Cross Cemetery
• Most Holy Trinity Cemetery

• Mount St. Mary Cemetery – Flushing
• Our Lady of Mount Carmel Cemetery – Astoria
• St. John Cemetery – Middle Village
• St. Monica Cemetery – Jamaica

• St. Charles / Resurrection Cemeteries – Farmingdale
• St. Mary Star of the Sea Cemetery – Lawrence
• Trinity Cemetery – Amityville

Saint Vincent's Catholic Medical Center – Closed

• Roman Catholic Archdiocese of New York
• Irish Americans in New York City
• History of education in New York City
• History of the Catholic Church in the United States

• Official Site

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