Inside notorious and influential struggles to define what it means to be “un-American,” illuminating the complex evolution of the term throughout US historyThe term “un-American” has been wielded as a powerful tool throughout US history, from Jefferson’s vision of the early Republic to the Trump era, yet no objective definition has ever been universally agreed upon. For the first time, George Lewis’s Un-Americanism offers a long history of this term, tracing what it has meant to whom through close looks at the most prominent contests for control of its definition and deployment. Lewis examines case studies that show politicians using the idea of the un-American to advance their agendas, organizations using it in racial nationalist campaigns, and federal committees using it in investigations such as those of the anticommunist “Red Scare” of the Cold War, along with activists and coalitions who have countered rhetoric of the “un-American” by claiming their own use of the term. In these chapters, Lewis delves into the role of institutions and organizations such as the American Legion, the House Un-American Activities Committee, and the American Civil Liberties Union. Lewis paints a compelling picture of how the term has both shaped and been shaped by the country’s social and political landscape. Un-Americanism offers a profound analysis of how this term has drawn and redrawn lines between what is considered “good” or “bad” politically. By exploring its complex evolution, the book highlights how the term has impacted each generation’s understanding of national values and American identity. Lewis challenges readers to reflect on its ongoing influence in defining who truly belongs in the American story.