The present volume by Falk Flade describes the construction and operation of cross-border energy networks in Eastern Europe. It examines transnational electricity, oil, and gas transmission systems and their short- and long-term implications for Poland. Covering a time span of roughly 150 years between the second half of the 19th century and the year 2016, the focus is on the socialist period between the late 1940s and the beginning of the 1990s. The role of Poland receives special attention and furthermore, other countries of the former Eastern Bloc such as Czechoslovakia, the GDR, and especially the Soviet Union are included. The book focuses on three case studies. It compares the development of the electricity grid Mir (Russian for peace), the crude oil pipeline Druzhba (Russian for friendship), and the natural gas pipeline Soyuz (Russian for union). The comparison facilitates the tracing of changing modes of cooperation between socialist countries in the Eastern Bloc regarding planning, construction, and usage of transnational energy infrastructures. The study is based on the theoretical approach of Large Technological Systems. This approach focuses not only on isolated artefacts such as pipelines or electricity transmission lines, but takes into account the technical, economic, political, and cultural context. It assumes that technical core and social context are inseparable and thus avoids technological determinism. Therefore, it allows to give answers to the organizational and economic as well as to the power-political dimensions of transnational energy infrastructures in the Eastern Bloc.