AbstractGrowing levels of polarization and out-group hostility have become fashionable explanations for the caustic politics of the Trump presidency. However, partisan and ideological identities cannot explain popular attraction to Trump’s anti-elite and populist rhetoric, nor can polarization and sorting account for rising levels of mass identification as political independents. In light of these discrepancies, we offer an explanation for the Trump era unrelated to traditional left-right identities and ideologies: anti-establishment orientations. We argue that much of what is interpreted as an expression of partisan and ideological extremism or polarization is actually the product of a deep-seated antagonism toward the broader political establishment. We first exhibit the individual-level correlates of anti-establishment orientations, finding that people holding strong anti-establishment views exhibit relatively high levels of anti-social personality traits and distrust of others. We then show that anti-establishment orientations are more predictive than left-right orientations of beliefs in conspiracy theories regarding COVID-19, QAnon, and voter fraud. Most importantly, we demonstrate that, while anti-establishment orientations are positively related to support for Donald Trump, they are negatively related to support for Joe Biden and both major parties. In short, the toxicity emblematic of the Trump era—support for outsider candidates, belief in conspiracy theories, corrosive rhetoric, and violence—are derivative of antipathy towards the established political order, rather than a strict adherence to partisan and ideological dogma. We conclude that Trump’s most powerful and unique impact on American electoral politics is his activation, inflammation, and manipulation of preexisting anti-establishment orientations for partisan ends.