This article examines the issue of translation in the writing of Haroldo de Campos through a study of his personal library and the Roman Jakobson archive at MIT (Massachusetts Institute of Technology), which contains their exchanges between 1966 and 1981. From these sources Haroldo’s intertexts and his intellectual networks are reconstructed, and his theory and practice of translation is historicized, shedding light also on Haroldo’s conception of literature and culture.