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Naturalization is the conferral of U.S. citizenship after birth, upon someone who does not have U.S. citizenship. Congress has full legislative authority over naturalization under its naturalization power in Article I, Section 8 of the Constitution. Exercising its naturalization power, Congress passed the Immigration and Nationality Act (INA) to govern all naturalization procedures. An applicant must follow the INA and may not become a citizen through state laws or courts’ equitable powers. Naturalized citizens have all the same rights and responsibilities as a natural born citizen except for presidential eligibility. To be eligible for naturalization, an applicant must be at least 18 years old and deemed mentally competent. Neither states nor Congress may abridge the right of an applicant to become a naturalized U.S. citizen based upon the applicant's race, sex, or marital status. Applicants bear the burden of proving by a preponderance of the evidence that they have met every eligibility requirement. After proving eligibility, an applicant must meet a few elements

One element involves an English literacy test. The applicant must demonstrate some comprehension in understanding, speaking, reading, and writing the English language unless the applicant suffers from a disability that prevents compliance with this requirement. Additionally, the applicant must demonstrate some knowledge regarding basic United States history and some knowledge regarding the governmental system within the United States. The disability exemption applies to this civics requirement as well.

A second element requires the applicant to have previously lived lawfully within the United States for at least five years. During those five years, the applicant must have remained physically present within the country for at least half of that time. Undocumented immigrants cannot later become naturalized U.S. citizens.

Third, the applicant must demonstrate good moral character. The Bureau of Citizenship and Immigration Services evaluates moral character within the context of a given community, comparing the applicant's record to the record of the average citizen residing therein.

Fourth, applicants must show a basic acceptance for the United States' form of government, which is typically referred to as "attachment" to the Constitution. An attachment to the Constitution means that the applicant will not try to effect political change through violence or infringe upon the rights and liberties of other U.S. citizens. The Bureau may disqualify applicants with histories that affiliate them with the Communist Party and other authoritarian regimes.

Fifth, naturalization requires applicants to have a favorable disposition toward the United States.

Courts generally apply a rebuttable presumption that applicants have good moral character, an attachment for the Constitution, and a favorable disposition toward the United States. While mental incompetency during the statutory period does not per se exclude an applicant, the Bureau of Citizenship and Immigration Services may use the mental health history as evidence against the legal presumption that the applicant has good moral character, attachment to the principles of the United States Constitution, and a favorable disposition toward the United States.

Federal Material

U.S. Constitution

  • Article I, Section 8 - Congressional Authority to Establish Uniform Rules of Naturalization
  • CRS Annotated Constitution:
    • Article I: Immigration
    • Search the Annotated Constitution

Federal Statutes

  • 8 U.S.C., chapter 12 - Immigration and Nationality
  • 8 U.S.C., chapter 13 - Immigration and Naturalization Service
  • 18 U.S.C., Part I, chapter 69 - Nationality and Citizenship (in the context of crimes)

Federal Regulations

  • 8 C.F.R. - Aliens and Nationality

Federal Agencies

  • Citizenship and Immigration Services
  • Department of Justice

International Material

  • Human Rights Treaties

​Additional Resources

  • American Immigration Council
  • USCIS's Immigration Law Glossary
  • ABA's Immigration Law Resources

[Last updated in July of 2023 by the Wex Definitions Team]