According to Section 215 of the U.S. Immigration and Nationality Act (8 U.S.C. 1185), it is illegal for an American citizen to enter or leave the U.S. on anything other than a valid American passport. This applies to dual citizens as well. A person holding both American and another country’s citizenship must enter and depart from the U.S. only on their U.S. passport.
Applying for a U.S. passport while outside the United States is a different process from applying for a U.S. passport while inside the United States. Although the application forms, supporting documentation, fees and finished products are the same everywhere, each U.S. embassy and consulate has different procedures for submitting and processing your final documents. During your appointment, the Consular Officer reserves the right to ask for additional documentation to support a passport application. Information and resources on the passport process can be found on the Department of State’s website: Travel.State.Gov.
As of January 1, 2016, U.S. embassies and consulates no longer offer the service of adding visa pages to U.S. passports.
Appointments are now required for all of the above services. To schedule an appointment for passport/citizenship services, go to U.S. Citizens Services Appointment System (this appointment calendar is ONLY to be used when you are appearing at the U.S. Embassy in Barbados; it is NOT to be used when a Consular Officer is visiting your island).