Naturalisation is the process that grants U.S. citizenship to lawful permanent residents (LPRs) who fulfil requirements established by Congress in the Immigration and Nationality Act (INA). In general, U.S. immigration policy gives all LPRs the opportunity to naturalise, and doing so is a voluntary act. The pool of people who are eligible to immigrate to the United States as legal permanent residents (LPRs) each year typically exceeds the world-wide level set by the Immigration and Nationality Act (INA). In an effort to process the demand for LPR visas fairly and in the national interest, LPR admissions are subject to a complex set of numerical limits and preference categories that give priority for admission on the basis of family relationships, needed skills, and geographic diversity. This book discusses United States naturalisation policies, and processes involved in immigrating and becoming a United States citizen.