You must provide acceptable documentary evidence bearing both the signature and a photo with a good likeness. This includes but is not limited to:
Valid U.S. Driver's License
State or Federal Work ID card
Student ID card
INS Alien Registration card
Note: Passport acceptance agents may request as many items off the list above as necessary to satisfy the identity requirement. Submission of one item off the list does not guarantee acceptability of ID. For further information or to download applications, visit the U.S. Department of State’s passport website.
Here are some additional sites which you might find useful if you are travelling outside the United States: