Walls are being built at a dizzying pace to separate us, cocoon us, and exclude us. The contributors to this volume illuminate the roles and uses of walls around the world—in contexts ranging from historic neighborhoods to contemporary national borders. They argue that more and more walls are being built even though they are a paradox in a neoliberal world in which people, goods, and ideas are supposed to move freely. The walls examined in this volume do not share a common form or type, but they do share a common political purpose: they determine and defend racist definitions of social belonging by controlling access and movement. The contributors include archaeologists, anthropologists, geographers, and sociologists. They bring different perspectives and insights to the scale, form, and impact of this phenomenon of "walling in" and "walling out."