This comprehensive resource explains six eras of immigration law, how and why immigration law has changed, who the major actors and organizations shaping immigration law are, and in what direction immigration law is likely to proceed in the near future. The United States has the most diverse population of any country in the world and is widely thought of as a nation of immigrants. U.S. immigration has been and continues to be a contentious political, cultural, and social issue. Much of current immigration policy is based on the Immigration and Naturalization Act of 1965, a law advocated by former President John F. Kennedy to establish a preference system of legal immigration. This book provides an authoritative analysis of current U.S. immigration law and the 1965 Act. It explains the precursor laws to the 1965 Act and their failure to resolve many critical problems, and details how and why the law was passed. It describes and profiles all the major actors and organizations that determine the politics of US immigration policy and details the impact—both foreseen and unanticipated—that the 1965 Act has had on the American economy, culture, demographics, and societal diversity. It offers an objective source for accessing an extensive list of the most important documents, governmental data, and scholarly discourse on U.S. immigration.