Established as a diocese in 1853, the Diocese of Springfield in Illinois serves more than 125,000 Catholics, in 28 counties in Central Illinois, a geographic area of 15,139 square miles. The diocese is divided into five deaneries, Springfield, Alton, Mattoon, Jerseyville, and Quincy consisting of 129 parishes, 36 elementary schools, 7 secondary schools, 1 university, and 8 Catholic hospitals within the boundaries of the Diocese. This local church is pastored by the Most Reverend Thomas John Paprocki, Bishop of the Diocese of Springfield in Illinois.

Each parish, school, or other agency has its own distinct history.

Information statistics circa 2021.

History of the Diocese may be found at History of the Diocese.