The Birgittine Order began in Vadstena around 1370. By the 1400s, many new monasteries were established by the order around the Baltic Sea and in other parts of Europe. In her dissertation, Hägglund examines the processes behind the founding of monasteries as well as the organization of the monasteries' economies and how they interacted with their surroundings. The focus is on donors and other individuals who supported the Birgittines in various ways. In return for their donations, private individuals were included in the monasteries' daily prayers, a privilege given only to those who had particularly supported the monasteries.

The dissertation's most important findings show that Birgittine monasteries were established in various types of societal contexts and that the monasteries adapted their organization based on their location and the individuals involved in their founding. Supporters of the Birgittines can be traced both to the local nobility with their estates in the countryside and to the bourgeoisie in the towns. The study is centered around three monasteries: Nådendal in the Diocese of Turku, Marienkrone in Stralsund, and Mariendal outside Tallinn. The focus is on donations, purchases, pledges, and exchanges of property with the monasteries. From these, Hägglund has mapped out the "Birgittine landscape," meaning the area where the monasteries owned land and had both spiritual and material influence.

The monastery located in Nådendal was part of an international organization with branches in various parts of Europe. Therefore, it is important to study how the activities of the Birgittines brought together local characteristics with a cross-border cultural context. Research on the medieval monasteries of the Birgittines is also important in a contemporary context. The Birgittines remain an enduring monastic order, and the order's founder, Saint Birgitta, is the patron saint of the European Union, whose 650th anniversary is celebrated in 2023.