How did secret services work? How was espionage organized and what kind of sources did it use? What did European secret services look like in 1914 and what was the main focus of the secret war? The texts in this edited volume examine these questions from different perspectives and reflect the specific historiographies in the respective countries. They also emphasize the broad nature of intelligence, the paramount importance of networking, and the variety of ways information was acquired. The authors of the volume highlight the complexity of intelligence, concentrating on Austria-Hungary, Russia, Germany and Italy. They look at the specific tasks of the services, examine different kinds of cooperation, and also consider the societal conditions of fin-de-siècle spy mania.