[5] As the Catholic population grew in Pennsylvania in the 19th century, the Vatican erected the Diocese of Pittsburgh in 1843 to cover the northwestern part of the state.

[8] Five months later, the Vatican changed course, returning O'Connor to Pittsburgh and making Young the second bishop of Erie.

[9] At the beginning of Young's tenure, the diocese contained 28 churches and 14 priests,[9] He established several Catholic schools and orphanages, and a hospital.

[14] Gannon organized religious education programs under the auspices of the Confraternity of Christian Doctrine in every part of the diocese and founded five regional high schools after age 80 alone.

To replace him, Pope Paul VI that same year named Auxiliary Bishop John Whealon from the Diocese of Cleveland.

Critics accused Watson of being too slow to implement the reforms of the Second Vatican Council, and met considerable opposition from the diocesan clergy.

Murphy soon visited every parish in the diocese and reorganized the diocesan administration to improve pastoral service to Catholics, delegating some of the bishop's authority and allowing more participation of religious and laity.

[19] In 1985, Murphy launched a spiritual growth process called RENEW, which attracted the participation of more than 20,000 people throughout the diocese and lasted until 1988.

[19] He established St. Mark Catholic Center and the Diocesan Committee on Human Sexuality in 1987 and merged several parishes and closed one school in 1989.

[1] Its historically significant parishes include:[22] Sean O'Hara complained to the diocese in April 2002 that he had been sexually assaulted by Reverend Chester Gawronski in 1977.

The 2018 Pennsylvania grand jury report would criticize Bishops Trautman and Murphy for allowing Gawronski to remain in ministry despite numerous allegations of sexual abuse.

[24] In his own defense, Trautman noted that he had set guidelines in 1993 on handling sexual abuse and established the diocesan Office for the Protection of Children and Youth in 2003.

In 2005, the Vatican tasked Bishop Mark Bartchak of the Diocese of Altoona-Johnstown, who had served as a priest in Erie, with investigating Presley.

[28] Parts of the memo read"I was not surprised to learn from other witnesses from the Elk County area, that there are likely to be other victims" and that "it is likely that there may be others who were also of the age for the offenses to be considered delicts, but to what end is it necessary to follow every lead?

[29] In April 2018, the diocese published a list of 34 priests and 17 laypeople who had been "credibly accused" of sexually abusing children.

[32] In August 2018, the Pennsylvania grand jury report was released, revealing 41 clergy in the Diocese of Erie with credible accusations of sexually abusing children.

[33][34] The report praised Bishop Persico, who acknowledged there had been a cover-up of sexual abuse crimes in the diocese.

[24] In October 2018, Reverend David Lee Poulson pleaded guilty to charges of corruption of minors and endangering the welfare of children.

[41] In August 2020, it was revealed that a total of 21 lawsuits were filed against the diocese since the 2018 grand jury report was released.