Between 1946 and 1953 ten conferences under the heading "Cybernetics. Circular, Causal, and Feedback Mechanisms in Biological and Social Systems" were held. Sponsored by Josiah Macy Jr., the so-called Macy Conferences mark perhaps the most important event in the history of science after WW II. Using new terms such as "information," "feedback," and "analog/digital" as starting point, the participants tried to develop a universal theory of regulation and control, that would be applicable to living beings as well as to machines, to economic as well as to mental processes, and to sociological as well as to aesthetical phenomena. These concepts permeate thinking in such diverse fields as biology, neurology, sociology, language studies, computer science, psychoanalysis, ecology, politics, and economy. They marked the epoch-making changes from thermodynamics to cybernetics (Wiener), from the disciplinary to control society (Deleuze), and from the industrial to information society (Lyotard). The Macy Conferences are of special historical/scientific value since they do not deal with completed texts yet, but rather with interdisciplinary negotiations about an emerging epistemology. This edition contains the complete transcription and protocols of all Macy Conference contributions, an introduction by the editor, and a previously unpublished introduction by Heinz von Foerster.