The first part of the book focuses on the origins of Logical Empiricism before World War I and the development of the Vienna Circle in "Red Vienna" (with the "Verein Ernst Mach"), its fate during Austro-Fascism (Schlick's murder 1936) and its final expulsion by National-Socialism beginning with the "Anschluß" in 1938. It analyses the dynamics of the Schlick-Circle in the intellectual context of "late enlightenment" including the minutes of the meetings from 1930 on for the first time published and presents an extensive description of the meetings and international Unity of Science conferences between 1929 and 1941. The chapters introduce the leading philosophers of the Schlick Circle (e.g., Hans Hahn, Otto Neurath, Rudolf Carnap, Philipp Frank, Felix Kaufmann, Edgar Zilsel) and describe the conflicting interaction between Moritz Schlick and Otto Neurath, the long term communication between Moritz Schlick, Friedrich Waismann and Ludwig Wittgenstein, as well as between the Vienna Circle with Heinrich Gomperz and Karl Popper. In addition, Karl Menger's "Mathematical Colloquium" with Kurt Gödel is presented as a parallel movement. The final chapter of this section describes the demise of the Vienna Circle andthe forced exodus of scientists and intellectuals from Austria. The second part of the book includes a bio-bibliographical documentation of the Vienna Circle members and for the first time of the assassination of Moritz Schlick in 1936, followed by an appendix comprising an extensive list of sources and literature.