According to the legend, the monastery was founded in 1136 by Siginand, prior of the abbey of Moutier-Grandval, who got lost in the deep forest of the High Jura while hunting a wild boar and was unable to find his way out. He vowed to found a monastery if he managed to return safely to Moutier, which he did four days later. To the monastery he founded in accordance with his vow he gave the name of "belle laie". According to other sources, the monastery was probably founded as a result of the influence of the Bishop of Basel on the south-west border of the diocese of Basel with the territory of the Abbot of Moutier-Grandval. The foundation was confirmed by Pope Innocent II in 1142. There are numerous spelling variations from the early years of the monastery: Balelaia, Belelagia, Belelai, Belilaia, Bellale, Bella Lagia, Bellelagia and Bellilagia. The name comes from the Vulgar Latinbella lagia. The abbey possessed various estates widely scattered. It was the mother-house of several other foundations, including Grandgourt Priory, Gottstatt Abbey and Himmelspforte Abbey at Grenzach-Wyhlen in Baden-Württemberg. Bellelay was under the authority of the diocese of Basel, but operated as an independent lordship under the terms of a protection contract agreed with Bern and Solothurn and also with Biel in 1516. Although the abbot had the right of the low justice in the abbey's immediate territory, and was awarded the right to the use of the ring, the mitre and the cross at the Council of Constance in 1414, it does not seem that Bellelay was ever an Imperial abbey. The buildings were ransacked during the Swabian War in 1499. During the Protestant Reformation some of the residents converted to the new faith. However, thanks to the treaty with Solothurn the monastery was spared the effects of the Thirty Years' War. The abbey reached its golden age in the 18th century as a renowned place of education for the sons of European nobility. During the 18th century the monastery buildings were rebuilt and a new church building was dedicated in 1714. The monastery university opened in 1772 and by 1779 it had 62 pupils from throughout Europe. A new dormitory wing was added in 1782 to accommodate the growing student population and by 1797 there were about 100 students at Bellelay.
Dissolution
In 1797 the buildings were occupied by French troops and secularised. The precious furnishings were sold at this time – an altar from Bellelay, for example, is now to be found in the parish church of Our Lady of the Assumption in Saignelégier. In the 19th century the monastery premises were used as a watch factory, then as a brewery and finally as a glass factory. In 1890 the Canton of Bern acquired the site, from which time the monastery buildings have been used as a psychiatric clinic. Since the end of the 1960s the premises have also been used for concerts and exhibitions by the Fondation de l'Abbatiale de Bellelay.
