CARPI, DIOCESE of. - An episcopal see in the province of Modena, C., originally a possession of Countess Matilde, passed under the dominion of the Holy See (1115-1225) and subsequently of Modena; in 1319 it was raised to an independent principality as an appanage of the Pio family until 1519. As a result of the wars between Carlo V and Francesco I, Prince Alberto Pio, known for his writings against Erasmus, was deprived of his principality after the battle of Pavia; it was invaded by the Imperial forces, and Carlo V entrusted it to Alfonso d'Este, Duke of Ferrara. From then on it remained in the possession of the Este family.
In 1779 Pio VI, at the request of Francesco III, Duke of Modena, raised C., which had been ecclesiastically subject directly to the Roman Curia since the time of Giulio II, to an episcopal see, appointing Francesco Benincasa, a former Jesuit from Sassuolo (Reggio Emilia), who governed it until 1794. In 1855 it became part of the metropolitan district of Modena. The Cathedral, built under the reign of the Lombard king Astolfo, was entirely rebuilt and embellished by Alberto Pio in 1516. The diocese covers 869.75 sq. km. and currently (1948) has 95,000 inhabitants, 36 parishes, 83 diocesan priests, and 7 regular clergy.