OSMA, DIOCESE OF. — Diocese in the province of Soria in Old Castile (Spain). It has a surface area of 8,549 sq. km. with a population of 188,900 all Catholic, distributed in 429 parishes, served by 315 diocesan priests and 80 religious; it has a seminary, 8 male religious communities and 20 female (Ann. Pont., 1952, p. 304). The see of the diocese is located in the small town of Burgo de Osma.
The origins of the diocese are somewhat uncertain. One of its bishops, GIOVANNI, attended the Council of Toledo in 597. Devastated during the Moorish occupation (8th–11th centuries), the diocese was re-established in 1088 and in 1103 it was taken possession of by ST PETER OF OSMA.
In the mid-16th century Bishop PETER ALVAREZ DE ACOSTA, under the direction of the Italian artist GIOVANNI DI JUNI, enlarged the College of St Catherine, which later became a university and was suppressed by Charles III in the 18th century.
The diocese, formerly a suffragan of Toledo and since 1851 of Burgos, comprises part of the provinces of Burgos and Soria and a small strip of that of Segovia. The cathedral, dating from the 13th century, has the high altar by GIOVANNI DI JUNI (1554). The patron saint of the diocese is ST PETER OF OSMA.