Naturalization is the process by which U.S. citizenship is granted to a foreign citizen or national after he or she fulfills the requirements established by Congress in the Immigration and Nationality Act (“INA”).  To apply for naturalization, file Form N-400, Application for Naturalization. You may qualify for naturalization if: you have been a permanent resident for at least 5 years and meet all other eligibility requirements, you have been a permanent resident for 3 years or more and meet all eligibility requirements to file as a spouse of a U.S. citizen, you have qualifying service in the U.S. armed forces and meet all other eligibility requirements and your child may qualify for naturalization if you are a U.S. citizen, the child was born outside the U.S., the child is currently residing outside the U.S., and all other eligibility requirements are met.  Note: You may already be a U.S. citizen and not need to apply for naturalization if your biological or adoptive parent(s) became a U.S. citizen before you reached the age of 18.