Throughout the first half of the twentieth century, 32 states passed laws allowing involuntary sterilization on those deemed biologically “unfit”: convicted criminals, the disabled, the poor, and people of color. Texas, despite a history of violent racism, was not one of them. In The Purifying Knife, Michael Phillips and Betsy Friauf explore this curious instance of the Lone Star State’s exceptionalism. The first history of the eugenics movement in Texas, it is a narrative that intersects with debates over race, immigration, abortion, the role of women in society, homosexuality, medical ethics, and the politics of disability in the state—debates resonating today in Texas and beyond.From the mid-nineteenth to the mid-twentieth centuries, Americans embraced eugenics. Yet the Texas legislature ultimately rejected nine of ten laws advocated by the state’s eugenicists and their predecessors. Phillips and Friauf trace this unlikely resistance to a variety of influences: wealthy cotton growers concerned that the anti-immigrant politics of the eugenics movement would deprive them of a source of easily exploitable labor; a populist distrust of higher education and the academic elites who enthusiastically supported the eugenics movement; and the forces of anti-Darwinist fundamentalism and pre-millennial dispensationalism in the 1920s, among others. The Purifying Knife also details how eugenical ideas survived long past their decline in the 1940s and have entered a disturbing afterlife in the late twentieth and early twenty-first centuries.A thoroughgoing look into a rare case where the eugenics movement “failed” in spite of its power in the United States and around the world—while still wielding a toxic influence—Phillips and Friauf’s work offers insight into the history of the LGBTQ community, abortion, and immigration policies in Texas, and persuasively argues that the long arc of eugenics history has helped shaped contemporary politics in the Lone Star State.