The Abbey of San Clemente a Casauria is an abbey in the territory of Castiglione a Casauria, in the province of Pescara, Abruzzo, central Italy.
The abbey was founded in 871 by Louis II, grand-grandson of Charlemagne, after a vow made during his imprisonment in the Duchy of Benevento. Initially entitled to the Holy Trinity, it was dedicated to St. Clement when the latter's remain were brought here in 872.
In its history the abbey was plundered several times: by the Saracens in 920 and repeatedly by the Norman count Malmozzetto between 1076 and 1097. After this destructive episode, the Benedictine abbot Grimoald promoted the rebuilding of the church, which was reconsecrated in 1105. However, the works ended only in the late 12th century under abbot Leonate (1152-82, cardinal from 1170).