Become a U.S. citizen through naturalization Granted to Person with more than 2 crimes. Now he is a U.S. Citizen. Adapting is the process through which a migrant to the United States of America can become a U.S. citizen. Only certain immigrants are eligible: those who either have been green card holders (permanent residents) for 3–5 years or meet various military service needs. Lawful U.S. release can be granted through the naturalization process or acquisition of immunity. The difference is that asset is given because of the person’s relationship to U.S. citizens, whereas naturalization requires a set of requirements for adults.