The number of monks and lay brothers living in Kloster Buch has not been passed on. In the late Middle Ages most monks hailed from the local and neighbouring areas, the furthest known place of origin was Halle (Saale). In 1433 a manuscript bible was made in the monastery, and in 1441 the abbot gained privileges ordinarily reserved to bishops, such as to wear a mitre and a bishop's ring during Solemn Mass, and to consecrate objects for liturgical use. In the same year, the abbey was awarded a coat of arms by the Council of Basel, showing the Lamb of God, a flag with the Christian cross, and three roses symbolising Mary, the patron saint of the Cistercian order.