The two most common ways to naturalize are for individuals who have been permanent residents for five years or more; and for individuals who are married to a US citizen and who have been permanent residents for three years.
The important requirements are:
1. Permanent residence (i.e. having a green card) for five years (or three years if married to a US citizen),
2. Show that were physically present in the US for 30 months (or for 18 months if you are married to U.S. citizen).
3. Can speak, read and write basic English, and have an understanding of U.S. history and government (civics).
4. Show that you support the principles of the U.S. Constitution and you are willing to swear an oath to the United States.
5. And that you are a person of “good moral character.”
The requirement of a “good moral character” is so to say a catch-all requirement, as it may encompass a whole range of conduct, which could potentially disqualify an applicant. A good moral character is a term of art, which is defined in Section 101(f) of the Immigration and Naturalization Act (INA). However, in general terms, it means that the applicant in the last 5 years, immediately preceding the application for naturalization:
• Was not arrested, or if arrested, the crime does not disqualify them
• If arrested, is not currently on probation, parole, or under a suspended sentence,
• Reporting his/her income on their Federal and State tax returns
• Was not involved in any type of immigration fraud
• Did not fail to support his/her dependents
• For certain male residents registered with the selective service,
• And various other factors.