For most of us, sex is intensely private. Few of us want our hidden, innermost desires and erotic practices made available for public scrutiny. But when we look at our contemporary world’s most divisive public debates – over reproductive rights, public health resources, immigration, marriage equality, even people’s access to public restrooms – we can’t help but notice that sex comprises a vital part of public discourse that shapes systems regulating people’s access to the rights, privileges, and protections of citizenship. Who we love/desire and the kinds of sex acts we participate in all influence our capacity to belong and to participate as full citizens. In short, if we look closely at the most urgent social issues around us, we will find that sex is anything but a private matter. To investigate how and why governmental apparatuses seek to control the sexual behavior of citizens in the interest of making racial segregation and immigration exclusion appear natural and proper, we will explore the complex matrix of state laws prohibiting people of supposedly different races from legally marrying, and efforts to curtail the reproduction of certain people while encouraging others to have more children. Studying these and other, more current episodes of state control over seemingly “private” or intimate matters reveals how dominant assumptions about race difference are supported by taken-for-granted knowledge about “unnatural” or even “dangerous” desires.