Foreign citizens who want to acquire U.S. passports must first become citizens of the United States, according to the U.S. Department of State. Because the United States recognizes dual citizenship, a foreign citizen who is also a U.S. citizen can acquire a U.S. passport, states About.com.
Applicants for U.S. passports must submit evidence of citizenship by showing a U.S. birth certificate, Consular Report of Birth Abroad, valid U.S. passport, naturalization certificate or certificate of citizenship, according to the U.S. Department of State. If one of these documents is not available, applicants can present secondary evidence of citizenship in the form of a birth affidavit, delayed birth certificate or a letter of no record, along with early public records such as census records, a baptismal certificate, hospital records, early school records and a doctor's report of post-natal care. Applicants born abroad can submit a foreign birth certificate along with evidence of the U.S. citizenship of at least one parent.
Applicants qualify for naturalization as U.S. citizens if they have lived as permanent residents in the United States for at least 5 years, have been permanent resident spouses of U.S. citizens for at least 3 years, or have qualifying service in the U.S. military, as reported by the U.S. Citizenship and Immigration Services. The process of naturalization involves submitting Form N-400 Application for Naturalization, having biometrics taken, going for an interview and taking an oath of allegiance.