[2][3] The Diocese of Rockford comprises the counties of Boone, Carroll, DeKalb, Jo Daviess, Kane, Lee, McHenry, Ogle, Stephenson, Whiteside and Winnebago.

It was estimated that 15,000 to 20,000 Native American converts and French trappers and settlers throughout the region were tended to by these Jesuit missionaries.

After the American Revolution ended in 1783, Pope Pius VI erected in 1784 the Prefecture Apostolic of the United States, encompassing the entire territory of the new nation.

[8] That same year, Bishop James Van de Velde of Chicago purchased land for the first Catholic church in Aurora.

With the 1917 entry of the United States into World War I, Muldoon ministered to soldiers and recruits at Camp Grant, the US Army facility in Rockford.

During his tenure, Hoban opened many elementary and high schools in the diocese, modernized charitable institutions, and established a diocesan newspaper.

The next bishop of Rockford was Monsignor John Boylan from the Diocese of Des Moines, appointed by Pius XII in 1942.

During his tenure as bishop, Boylan was able to reduce the diocese's debt while adding new parishes and schools to meet population growth.

After Boylan died in 1953, Pius XII named Reverend Raymond Hillinger from Chicago to replace him that same year.

[15] In 2006, Andrew Howell, a Colorado man sued the diocese, claiming he had been abused by Joffe when he was eight years old at St. Mary Parish in Woodstock in the late 1970's.

In 2002, after the story appeared in the media, Bishop Doran confirmed that Reverend Harlan Clapsaddle, a diocese priest, had sexually abused three brothers when they were children during the 1970s.

The family said they urged Doran to report Clapsaddle to the police and search for other victims, but he instead told them to stay silent about it.

[19] In November 2018, Bishop Malloy released a list of 15 clerics, including one deacon and one brother, from the diocese who had been accused of acts of sexual abuse from 1925 to 1991.

While ministering in the Diocese of San Bernardino in California in 2014, Jablonski allegedly made remarks to a young boy that constituted sexual grooming.

[22][23] On September 30, 2000, John Earl, a Rockford Catholic priest, drove his car into the Northern Illinois Health Clinic after learning that the FDA had approved the drug RU-486.