Roman Catholic Diocese of Reggio Emilia–Guastalla

The Diocese of Reggio Emilia–Guastalla (Latin: Dioecesis Regiensis in Aemilia–Guastallensis) is a Latin diocese of the Catholic Church in Emilia-Romagna, Italy. It has existed in its current form since 1986. In that year the historical Diocese of Reggio Emilia was united with the Diocese of Guastalla. The diocese is a suffragan of the Archdiocese of Modena–Nonantola.

Originally the diocese was part of the ecclesiastical province of Milan, then it was suffragan to the Archbishop of Ravenna. Because of the schism of the Antipope Clement III, Pope Paschal II released the dioceses of Emilia, including Reggio, from obedience to the church of Ravenna, and made them directly subject to the Holy See (Rome), but twelve years later Pope Gelasius II restored the previous status. In 1582 the diocese of Bologna was raised to the status of a metropolitan archbishopric. Reggio was made a suffragan of the archdiocese of Bologna, by Pope Gregory XIII in the bull Universi orbis of 10 December 1582. Modena was raised to the status of an archdiocese and its bishop to the status of a Metropolitan Archbishop by Pope Pius IX in his bull of 22 August 1855, entitled Vel ab antiquis. Reggio became one of its suffragans.