This volume presents for the first time one of Jacques Lacan's most important lectures in German translation: On Structure as the Interference of an Other as a Condition of a Subject. He delivered it at the famous Structuralism Conference at Johns Hopkins University in Baltimore in 1966, which became known as The Structuralist Controversy. The lecture consolidates philosophical questions and themes from his research over two decades: the distinction between the subject of the statement and the subject of the stated, the reception of Bertrand Russell's set paradox, Gottlob Frege's theory of number genesis, and the insight into the precarious status of the unconscious, which is caught in repetitions to continually fill the subject's existence anew. Lacan also provides his listeners with illustrative representations of the psyche with references to it.