Communism's collapse and the rise of globalization have served to magnify the tensions between population flows and traditional notions of inviolable national borders. In this impressive book, Joppke points out that universal principles of justice and freedom of movement often conflict with the primacy of sovereign borders and national identity. Focusing on the United States, Germany, and Britain, he finds that states are often pulled in multiple directions, attempting to control their borders while facing human rights constraints on national sovereignty. As they create new membership categories for new immigrants, they also come under pressure to establish unitary citizenship rights. Still, each country has handled these pressures differently. America's immigrant tradition and civil-rights culture has contributed to a relatively open immigration regime, whereas Britain's colonial legacy has led to restrictions on immigration as well as the thorough assimilation of former colonial peoples. Meanwhile, Germany's legacy of ethnic citizenship and its guest-worker tradition have created distinct dilemmas of permanent settlement. By identifying these three patterns, Joppke nicely demonstrates the influence of national political and cultural traditions in framing immigration and citizenship rights. Most intriguing is his claim that today's immigrants-aided by modern technology-resist assimilation more than previous generations, making the diaspora a permanent feature of world political life.