The Roman Catholic Diocese of Saginaw (Latin: Dioecesis Saginavensis) is a Roman Catholic diocese covering eleven counties in Michigan, USA. It was founded on February 26, 1938; the first bishop was William Francis Murphy. On May 20, 2009, Pope Benedict XVI named Bishop Joseph Robert Cistone, auxiliary bishop and vicar general of the Archdiocese of Philadelphia and titular bishop of Casae Medianae, as the sixth Bishop of the Diocese of Saginaw. He replaced Robert James Carlson, who became Archbishop of Saint Louis on April 21 of that year.