Naturalization - the process by which legal U.S. immigrants (permanent residents) attain full U.S. citizenship status - begins with the filing of USCIS Form N-400. The applicant must be prepared to satisfy numerous statutory requirements at the time the petition is filed and later, when interviewed for naturalization. The USCIS web site contains detailed information and materials on such topics as eligibility requirements, exclusions and waivers from naturalization, English history sample test questions, forms, and other helpful information. You can find this information at:

http://uscis.gov/graphics/services/natz/index.htm

To be eligible for U.S. citizenship, applicants must maintain continuous U.S residence for a period of several years, the majority of which must be spent physically present in the U.S. Continuous absence from the U.S. for a period of more than 6 but less than 12 months may lead to a presumption of a break in continuous residence (though this is rebuttable). Continuous absence for more than 12 months will automatically break continuous residence for naturalization purposes and may also lead to loss of permanent resident status.

A legal permanent resident who intends to travel abroad for a period of 6 months or longer may file an application with the USCIS to preserve residence for naturalization purposes. If the applicant intends to travel abroad for a period of more than one year, he or she can also file an application for a re-entry permit so as not to abandon residence.

Preservation of status for naturalization purposes is available to people who have been physically present in the U.S. (without interruptions) for not less than one year since becoming a permanent resident and who are engaged by a U.S. entity to work abroad. The application must be made before the expiration of one-year abroad using USCIS Form N-470. If the resident's absence is unrelated to employment with a U.S. employer, he or she may not qualify for this benefit.

Application for permission to re-enter the U.S. after an extended absence abroad is made on USCIS Form I-131. The application must be filed with the USCIS before the resident’s departure while he or she is still physically present in the U.S. A resident who is granted permission to return to the U.S. under these circumstances must nevertheless maintain permanent ties to the United States, the absence of which may lead to a determination of abandonment, even in instances where a re-entry permit is granted.