This collection of articles by Jürgen Sarnowsky covers 20 years of research dedicated to the military orders in general as well as to the Hospitallers and Teutonic Knights. Four of these have been translated into English especially for this volume and two articles are published here for the first time. Section one contains five papers on the self-perception, statutes, and historical writing of the orders, and on their relationship with the crusading movement. In section two, the example of the Hospitallers is used to discuss some problems of the central administration of the orders (chapters general, finances) and its relationship to the provinces (the situation in the English priory, the functioning of visitations). Section three is dedicated to the 'order states' of the Hospitallers in the Aegean and the Teutonic Knights in the Baltic. Three articles give a comparison of their rule, their self-perception, and employment of ships, two other papers deal with the legislation and the situation of the church on Rhodes, and two with certain aspects of the foreign policies of the Teutonic Knights in Prussia. The last section focuses on internal features of the order's history. Three articles compare the role of the priests, the masters, and of women in the military orders, and this is complemented by smaller studies on the life of the brethren and the death of the masters of the Hospitallers on Rhodes.