This first volume of the Series "Quaderni del Centro Studi Americani" is dedicated to the much debated topic of Post-Truth. Taking its cue from the growing relevance of issues related to the controversial topic of post-truth, the 2023 edition of the Center for American Studies Seminar on U.S. History, Literature, and Culture aimed at analyzing the various facets and implications of this concept from historical, philosophical, and literary perspectives. The speakers were invited to reflect on the meaning of 'post-truth,' elected word of the year in 2016 by the Oxford Dictionaries; characterized by a marked polysemy and a strong divergence (at times even incongruence) in its uses, the term had already saturated the public debates in 2017. Post-truth is sometimes understood as a mode of communication in which objective facts are less relevant than emotions and personal beliefs; in other cases, it is used to indicate the dissemination of deliberately and consciously false information (only to mention two of the most common meanings). To be sure, this notion marks a profound paradigm shift in our time.