This chapter reviews evidence regarding the radicalization of academia. It is organized into the following major sections: A review of the evidence on the psychology of left-wing extremism and left-wing authoritarianism; a review of selected real-world events emblematic of left-wing extremism and authoritarianism in the American academy; we then review national surveys of Americans and American professors, which show that both the mainstream left and far left are massively overrepresented in the American academy, and this skew seems to be in the process of becoming even more extreme. This is then followed by a review of surveys showing that scholars on the right report far greater experiences of a hostile work environment than do scholars on the left and substantial minorities and sometimes majorities of scholars on the left express willingness to purge and punish their opponents. Evidence provided by surveys of academics also shows that academia is increasingly populated by demographic groups less supportive of free speech and academic freedom. As individuals hostile to free speech and academic freedom ascend into leadership positions in major academic organizations and institutions, they can be expected to implement policies reflecting that hostility. A review of recent developments at major universities, the National Institutes of Health, the apex science journal Nature, and the Society for Personality and Social Psychology confirms this expectation. We end by reviewing some of the ways the radicalization of the American academy has produced ideological corrupt and demonstrably invalid scholarship. We end by making some recommendations for reversing these trends but we are not optimistic that any will actually be adopted to any significant degree.