For people born in the United States their birth certificate is their proof of citizenship. For those born outside of the United States a Certificate of Citizenship may be used as proof of United States Citizenship. To apply for a Certificate of Citizenship a person must file a Form N-600. 

This certificate is intended to be filed by individuals with a parent who is a United States Citizen. Individuals may file this paperwork for themselves or their child (if their child has a parent who is a U.S. Citizen).

When applying for this certificate an individual should gather together a few documents. These include the birth certificate of the U.S. parent, the petitioner's birth certificate, evidence of parent’s citizenship, and two professional passport style photos.

The photos needed for this application can be done by the applicant but USCIS has suggested that green card applicants use a photo service in order to obtain photos that meet their standards.

What Can I Use a Certificate of Citizenship for?

A Certificate of Citizenship can be used to get a U.S. passport. It is also a document that can be used when an individual wishes to sponsor a family member through their green card application.