The theme of this collection of academic essays relates to the dimensions of Polish-German cooperation with regard to security, which has mainly occurred during the last 25 years since the signing of the 1991 Treaty on Good Neighbourliness and Friendly Cooperation between the Republic of Poland and the Federal Republic of Germany. Due to the complexity of Polish-German relations, it is also necessary to take their historical background into consideration. That is why some of the studies address historical aspects of the countries' bilateral relationship, i.e. those prior to 1991, which will provide the readers with a deeper understanding of the multifaceted nature of Polish-German relations. The contributions deal with Polish-German cooperation on issues such as domestic and foreign security and defence as well as with their cooperation at the regional level. The authors have not only used secondary sources in their studies but also legal and archival documents plus other official papers. Since the articles were written by a group of international political scholars and historians, they contain sources in a variety of languages, mainly Polish, German and English, which adds to this volume's value.