Guests and Aliens presents a comprehensive analysis of worldwide immigration by one of the world's leading experts on globalization. Putting the current "crisis" of immigration into a historical context for the first time, Sassen suggests that the American experience represents only one phase in a history of global border crossing. She describes the mass migrations of Italians and Eastern European Jews during the nineteenth and early twentieth centuries and the international dislocations—particularly after the end of World War II—that have engendered the "refugee" concept. Using these examples, Sassen explores the causes of immigration that have resulted in nations' welcoming incomers as "guests" or disparaging them as "aliens," and outlines an "enlightened approach" (Publishers Weekly) to improving US and European immigration policies.