This paper focuses on Roman Jakobson's general linguistics lectures in New York during World War II. These courses, that Claude Lévi-Strauss attended, have played a major role in the spreading of post-war "generalized structuralism". However, they only came to be known by the later testimonies of the two scholars and partial editions from the 1970s and 1980s. Therefore, this study aims at showing that taking into account unpublished sources can bring something new to our knowledge of these teachings. After the description of the institutional context of the École Libre des Hautes Études that housed this teaching, the list of Roman Jakobson's general linguistics classes is retraced and put in perspective with the unpublished notes that have been kept in his archives. Taking into account the preparatory manuscripts of these classes sheds light on the logic that governs Jakobson’s teaching at the École Libre, conceived as a critical reinterpretation of the Course in General Linguistics.