The Diocese of Pavia is a Latin diocese of the Catholic Church in Italy. It has been a suffragan of the Archdiocese of Milan only since 1817. Previous to the reorganization of the hierarchy in northern Italy by Pope Pius VII after the expulsion of the French and the Congress of Vienna, the diocese of Pavia had depended directly upon the Holy See, despite repeated failed attempts on the part of the Archbishops of Milan to claim control. The diocese has produced one Pope and Patriarch of Venice, and three cardinals.

The Archdiocese of Milan is a Latin Church ecclesiastical territory or archdiocese of the Catholic Church in Italy which covers the areas of Milan, Monza, Lecco and Varese. It has long maintained its own Latin liturgical rite usage, the Ambrosian rite, which is still used in the greater part of the diocesan territory. Among its past archbishops, the better known are Ambrose, Charles Borromeo, Pope Pius XI and Pope Paul VI.