Canonesses, like nuns, were religious women who lived in community; sources often refer to both as ‘sanctimoniales’. Yet there were differences: unlike nuns, canonesses made no permanent vows, did not relinquish private property, wore secular clothing, and performed various public duties. During the early 9th century, reforms aimed at bringing the lives of canonesses more in line with monastic observance. The ‘Institutio Sanctimonialium’, a rule for canonesses, was instituted at the Council of Aachen (816). Communities of canonesses reached their apogee in Germany during the 9th and 10th centuries, with several houses of canonesses closely tied to the imperial court; many canonesses were powerful and educated women. Yet, by the middle of the 11th century, reformers once again turned their attention to houses of canonesses, denouncing the canonical way of life as degenerate and urging that canonesses adopt a recognised rule.