Few issues have provoked as much controversy over the last decade as illegal immigration. While some argue for the need to seal America's borders and withdraw all forms of social and governmental support for illegal migrants and their children, others argue for humanitarian treatment--including legalization--for people who fill widely acknowledged needs in American industry and agriculture and have left home-country situations of economic hardship or political persecution. The study of illegal immigration necessarily confronts a broad range of migrants--from the familiar border crossers to...