The United States, often described as a nation of immigrants, has the most diverse population in the world. Immigration remains one of the most complex and contentious political, cultural, and social issues in the country. Much of today's policy stems from the Immigration and Naturalization Act of 1965, championed by President John F. Kennedy to establish a new preference system for legal immigration.This comprehensive volume explains the six major eras of immigration legislation, examines how and why laws evolved, and profiles the key actors and organizations shaping immigration policy today. It outlines the precursor laws to the 1965 Act, how they fell short, and the motivations and political context behind the Act's passage. The book also considers where U.S. immigration law may be headed in the near future. In addition, it explores the intended and unforeseen impacts of the 1965 Act on the American economy, demographics, and society at large. A curated selection of primary documents, government data, and scholarly sources supports this authoritative overview of immigration policy in the United States.