Who can apply

If you were not born in the USA and your biological or adopting parents are not US citizens, you can still become a US citizen via naturalisation process. Citizenship through naturalisation is the most common method to attain US citizenship for foreigners. You can apply once you are sure that you satisfy all of the following conditions:
 
- You are a foreign national with 5 years lawful permanent residence in the U.S. and at least half that time you were physically present inside the U.S.  with no periods of absence over six months at any single absence period; or You are a permanent resident for 3 years, who is currently married to a U.S. citizen, and has been married to the same U.S. citizen for the past 3 years

-you have lived in the district or state where you are filing your application for at least three months

-  you have not made your primary home in another country

-  you are at least 18 years old

- you are able to speak, read, and write in English

- you are able to pass a test covering U.S. history and government

- you have good moral character, and

- you are willing to swear that you believe in the principles of the U.S. Constitution and will be loyal to the United States.

Note: When parents become naturalised U.S. citizens, their children under 18 with green cards gain U.S. citizenship automatically.