The laws pertaining to Naturalization are very complex. They are contained in Section 316 of the Immigration & Nationality Act or "INA." Here below is a simplified explanation.
Applicants must be at least 18 years old.
Refer to the section, Naturalized Citizen's Children under Waivers, Exceptions, and Special Cases for information on applicants who are less than 18 years old. See Also INA §334
An applicant must have been lawfully admitted to the United States for permanent residence. Lawfully admitted for permanent residence means having been legally accorded the privilege of residing permanently in the United States as an immigrant in accordance with the immigration laws. Individuals who have been lawfully admitted as permanent residents will be asked to produce an I-551, Alien Registration Receipt Card, as proof of their status. See Also INA §316
Residence and Physical Presence
An applicant is eligible to file if, immediately preceding the filing of the application, he or she:
has been lawfully admitted for permanent residence (see preceding section);
has resided continuously as a lawful permanent resident in the U.S. for at least 5 years prior to filing with no single absence from the United States of more than one year;
has been physically present in the United States for at least 30 months out of the previous five years (absences of more than six months but less than one year shall disrupt the applicant's continuity of residence unless the applicant can establish that he or she did not abandon his or her residence during such period)
has resided within a state or district for at least three months
Good Moral Character Generally, an applicant must show that he or she has been a person of good moral character for the statutory period (typically five years or three years if married to a U.S. citizen or one year for Armed Forces expedite) prior to filing for naturalization. The Service is not limited to the statutory period in determining whether an applicant has established good moral character. An applicant is permanently barred from naturalization if he or she has ever been convicted of murder. An applicant is also permanently barred from naturalization if he or she has been convicted of an aggravated felony as defined in section 101(a)(43) of the Act on or after November 29, 1990. A person also cannot be found to be a person of good moral character if during the last five years he or she:
has committed and been convicted of one or more crimes involving moral turpitude
has committed and been convicted of 2 or more offenses for which the total sentence imposed was 5 years or more
has committed and been convicted of any controlled substance law, except for a single offense of simple possession of 30 grams or less of marijuana
has been confined to a penal institution during the statutory period, as a result of a conviction, for an aggregate period of 180 days or more
has committed and been convicted of two or more gambling offenses
is or has earned his or her principal income from illegal gambling
is or has been involved in prostitution or commercialized vice
is or has been involved in smuggling illegal aliens into the United States
is or has been a habitual drunkard
is practicing or has practiced polygamy
has willfully failed or refused to support dependents
has given false testimony, under oath, in order to receive a benefit under the Immigration and Nationality Act.
An applicant must disclose all relevant facts to the Service, including his or her entire criminal history, regardless of whether the criminal history disqualifies the applicant under the enumerated provisions. See Also INA 316
Attachment to the Constitution An applicant must show that he or she is attached to the principles of the Constitution of the United States. See Also INA §316
Applicants for naturalization must be able to read, write, speak, and understand words in ordinary usage in the English language. Applicants exempt from this requirement are those who on the date of filing:
have been residing in the United States subsequent to a lawful admission for permanent residence for periods totaling 15 years or more and are over 55 years of age;
have been residing in the United States subsequent to a lawful admission for permanent residence for periods totaling 20 years or more and are over 50 years of age; or
have a medically determinable physical or mental impairment, where the impairment affects the applicant’s ability to learn English.
See Also INA 312
United States Government and History Knowledge
An applicant for naturalization must demonstrate a knowledge and understanding of the fundamentals of the history and of the principles and form of government of the United States.
Applicants exempt from this requirement are those who, on the date of filing, have a medically determinable physical or mental impairment, where the impairment affects the applicant’s ability to learn
U.S. History and Government
Applicants who have been residing in the U.S. subsequent to a lawful admission for permanent residence for at least 20 years and are over the age of 65 will be afforded special condsideration in satisfying this requirement. See Also INA 312
Naturalization Test Questions for Applicants Meeting 65/20 Exception
Test Yourself on U.S. History
Sample U.S. History Questions with Answers
Oath of Allegiance
To become a citizen, one must take the oath of allegiance. By doing so, an applicant swears to:
support the Constitution and obey the laws of the U.S.;
renounce any foreign allegiance and/or foreign title; and
bear arms for the Armed Forces of the U.S. or perform services for the government of the U.S. when required.
In certain instances, where the applicant establishes that he or she is opposed to any type of service in armed forces based on religious teaching or belief, USCIS will permit these applicants to take a modified oath.