[1] Before and during the American Revolutionary War, the Catholics in all of the British colonies in America were under the jurisdiction of the Apostolic Vicariate of the London District in England.

Curtis also built St. Joseph Church in Wilmington, an orphanage, and a parochial school and segregated facilities for the African-American congregation.

Curtis retired in 1896 due to poor health and Leo XIII appointed Monsignor John Monaghan of the Diocese of Charleston as his replacement.

When Monaghan became bishop, the diocese had 25,000 Catholics, 30 priests, 22 churches and 18 missions, 12 seminarians, eight religious communities, three academies, nine parochial schools, and three orphanages.

[8] Monaghan retired in 1925 and Pope Pius XI replaced him with Monsignor Edmond Fitzmaurice from the Archdiocese of Philadelphia.

Fitzmaurice donated his personal residence in 1959 to provide a location for the founding of St. Edmond's Academy in Wilmington, which was named in his honor.

[8] Hyle also established St. Mark's High School in Wilmington and the University of Delaware's Newman Centre (Thomas More Oratory) in Newark.

During his tenure as bishop of Wilmington, Mulvee emphasized collegiality in his administration of the diocese, helped restructure the Delmarva Ecumenical Agency into the Christian Council of Delaware and Maryland's Eastern Shore, and founded three new missions and raised a fourth to parish status.

[8] Mulvee's tenure in Wilmington ended in 1995 when John Paul II named him as coadjutor bishop for the Diocese of Providence.

John Paul II named Auxiliary Bishop Michael Saltarelli of the Archdiocese of Newark as Mulvee's replacement in Wilmington in 1996.

During his tenure, Saltarelli oversaw an increase of over 60,000 Catholics in the diocese, ordained 23 priests and 47 permanent deacons, and constructed or renovated numerous churches, schools, and other facilities.

[13] After Saltarelli retired in 2007, Pope Benedict XVI named Auxiliary Bishop W. Francis Malooly of Baltimore to replace him.

Malooly was criticized by some Catholic news outlets for refusing to withhold communion from then Vice President Joseph Biden due to his position on abortion rights for women.

[15] Malooly retired in 2021 and Pope Francis appointed William Koenig of the Diocese of Rockville Centre as the new bishop of Wilmington.

Joseph Curry, a former altar boy at St. Dennis Church in Galena, sued the Diocese of Wilmington in August 2008.

The lawsuit claimed that the diocese knew that Carley had sexually abused parishioners at St. Ann's Church in Wilmington during the 1950s and early 1960s.

The crime happened on the beach at Indian River Inlet at a Catholic Youth Organization event when Dougherty was in the eighth grade.