Through birth abroad to two United States citizens
See also: jus sanguinis
In most cases, one is a U.S. citizen if both of the following are true:
Both parents were U.S. citizens at the time of the child's birth
At least one parent lived in the United States prior to the child's birth.
A person's record of birth abroad, if registered with a U.S. consulate or embassy, is proof of his or her citizenship. He or she may also apply for a passport or a Certificate of Citizenship to have his or her citizenship recognized.
[edit] Through birth abroad to one United States citizen
In most cases, a person is a U.S. citizen if all of the following are true:
One of his or her parents was a U.S. citizen at the time of the person in question's birth;
The citizen parent lived at least 5 years in the United States before his or her child's birth; and
At least 2 of these 5 years in the United States were after the citizen parent's 14th birthday (see note below).
A person's record of birth abroad, if registered with a U.S. consulate or embassy, is proof of his or her citizenship. Such a person may also apply for a passport or a Certificate of Citizenship to have his or her citizenship recognized.
Note: If born before November 14, 1986, a person is a citizen if his or her U.S. citizen parent lived in the U.S. for at least 10 years and 5 of those years in the U.S. were after the citizen parent's 14th birthday. The newer law does not apply retroactively.
Different rules apply for those born before December 24, 1952.