The first document that you need in order to apply for a passport is Form DS-11: Application for a U.S. Passport. Fill this form out online or by hand, but do not sign it until you are asked to at the acceptance facility. Be sure to include your social security number on the application. Form DS-11 is available on the Department of State's website or at a passport acceptance facility, such as a U.S. post office or embassy.
Proof of your U.S. citizenship must accompany the passport application. You can show citizenship with an expired, undamaged passport, a certified birth certificate, a naturalization certificate or a certificate of citizenship. You can also submit a consular report of birth abroad or certification of birth.
You must also submit personal identification when applying for a passport. Acceptable identification includes an expired, undamaged passport, naturalization certificate or valid driver's license. Current government and military IDs are also accepted. Photocopies of the front and back of your identification will be submitted with your passport application.
The final requirement for a U.S. passport application is a recent color passport photo measuring 2 by 2 inches. Shoot the photo with a white or plain background.