The first Catholic missionaries arrived in the Iowa area during the early 1830s, under the jurisdiction of the Diocese of St. Louis.

The building served as a church, city hall, courthouse, schoolhouse, public forum, and gathering place for the citizens of Davenport.

His duties included attending the communities of Muscatine, Burlington, Iowa City, Columbus Junction, DeWitt, Lyons, and Stephenson, Illinois, across the Mississippi River from Davenport.

When the German pastor at St. Kunigunda refused to serve the needs of Irish immigrants who settled in the west end, Pelamourgues built St. Mary's two blocks away.

Hennessy suggested locating the see of the new diocese in Des Moines, but the Vatican chose Davenport instead.

[5] He selected Monsignor John McMullen, vicar general of the Archdiocese of Chicago, to serve as the first bishop.

Reverend Henry Cosgrove, the diocesan administrator and cathedral rector, was appointed by Leo XIII as the second bishop of Davenport in 1884.

Sacred Heart Asylum later became St. Vincent's Home for orphans[1][7][8] Cosgrove supported the national Temperance Movement and called for a moral crusade in the diocese, especially in Davenport.

[9] In 1904, at Cosgrove's request, Pope Pius X named Reverend James J. Davis, vicar general and cathedral rector, as coadjutor bishop of the diocese to assist with its administration.

[11] After Davis died in 1926, Pope Pius XI named Reverend Henry Rohlman of the Archdiocese of Dubuque as the fourth bishop of Davenport.

[13] Pope Pius XII named Rohlman as coadjutor archbishop of Dubuque in 1944 and replaced him in Davenport with Bishop Ralph Hayes, rector of the Pontifical North American College in Rome.

[15] The National Catholic Welfare Council held a four-day conference in Davenport in 1949, focuring on the themes of industry, education, and rural life.

Hayes established the Papal Volunteers of Latin America in the diocese in February 1961 in response to a plea from Pope John XXIII.

O’Keefe joined with Bishops Arthur O'Neil of Rockford and John Franz of Peoria to create an office that assisted migrant workers with job and education services.

In 1991, O'Keefe announced a plan for clustering and closing smaller parishes, reflecting both the reduced number of priests and the lower diocese population.

Franklin revised the diocesan staff, creating an Office of Pastoral Services that combined the ministries of liturgy, education, and social action.

Four priests were named by the Vatican as chaplains to his holiness, eight laymen were honored as knights of St. Gregory the Great, three women received the honor of dames of the Order of St. Gregory the Great, and 11 men and women received the cross oro ecclesia et pontifice.

As a result of the bankruptcy, the diocese was forced to sell off property, including the bishop's residence, to pay for a financial settlement to sexual abuse victims.

[26] Amos had previously requested a small fixer-upper house to live in, believing the bishop's residence too big for him.

[27] The diocese also sold the chancery building, the St. Vincent Center, and its surrounding property to St. Ambrose University in May 2009.

At the same time, the diocese initiated a $22 million capital campaign to replenish diocesan finances and fund other projects.

However, the plaintiffs dropped their lawsuits in 1993 after an investigation revealed that the two women had fabricated the accusations against O'Keefe while together in therapy.

[34] In 2002, Bishop Franklin received allegations of sexual abuse of minors in the 1970s by Reverend William Wiebler.

After Wiebler confessed his crimes to Franklin, the bishop ordered him to enter the Vianney Renewal Center, a treatment facility for priests in Dittmer, Missouri.

[38][39] That same month, Bishop Amos announced that the board of trustees of St. Ambrose University had decided to remove O'Keefe's name from the school library.

[27] In 2014, documents revealed that Reverend James Janssen, who sexually abused boys and was laicized in 2004, stated in court during lawsuits that "I'm very sick.

In March 2020, the diocese announced that Reverend Robert Grant, a theology professor at St. Ambrose University, had been suspended from teaching and practicing ministry after a sex abuse allegation surfaced.

[45] The Congregation of the Humility of Mary founded Marycrest College in Davenport in 1939 as the woman's division of St. Ambrose.

The college began offering online graduate courses in 2002 and changed its name to Franciscan University.

The family's arms are described as, "Argent (white or silver), a chevron sable (black) between three cross crosslets fitchée of the second.