The book describes the control exercised by the National Socialist state over academic libraries and analyses their collaboration, in particular in the theft of books and the identification of 'Enemies of the Reich'. In addition, it deals with aspects of the identification and restitution of books stolen and confiscated between 1933 and 1945. This account presents the provisional findings of a research project conducted since 2006 by the Berlin State Library Prussian Cultural Heritage Foundation and the Max Planck Historical Institute/Max Planck Institute for the History of Science and funded by the Fritz Thyssen Foundation.