If you are researching options to immigrate to the U.S., keep in mind that you may already have a claim to U.S. citizenship if:
The laws on who can acquire U.S. citizenship have changed throughout the years. If you were born between November 14, 1986 and the present time, this article will provide information to help you determine whether or not you acquired U.S. citizenship from your parent(s). You can read more articles about U.S. citizenship and naturalization and see the rules for earlier time periods at Nolo's section on Acquiring or Deriving Citizenship Through Parents.
The most common way to become a U.S. citizen is to be born in the United States. You may also become a U.S. citizen later on in life if you hold a green card first (in most cases) and then naturalize (which you'd do by submitting an application, taking certain tests, and swearing an oath of allegiance). If your parents naturalized and you were a permanent resident (green card holder) who was under 18 at the time, you may be eligible to "derive" citizenship without submitting an application of your own.
Even if you were born in a foreign country, you may have automatically become a U.S. citizen at birth (in other words, "acquired" your citizenship) if one or both of your parents were U.S. citizens on your date of birth and they fulfilled certain residency requirements. In this case, you do not have to naturalize—you are already a citizen. To obtain proof of your status, you can submit an application for a Certificate of Citizenship to U.S. Citizenship and Immigration Services (USCIS), which you can then use to obtain a U.S. passport.
Special rules apply to children born overseas to a surrogate, however. See Will Our Surrogate Child Born Overseas Acquire U.S. Citizenship From Us?.
If both your parents were U.S. citizens on your date of birth, and you were born between November 14, 1986 and the present, you have acquired U.S. citizenship if at least one parent lived in the United States at some point prior to your birth. You will, in order to obtain a Certificate of Citizenship, need to provide USCIS with evidence that this parent had a U.S. residence (such as an identification card, school record, tax transcript, or lease).
You yourself do not need to have lived in the U.S. at any time, nor met any other conditions to keep your citizenship.
If you have only one U.S. citizen parent, and you were born between November 14, 1986 and the present, you will need to gather additional evidence to show USCIS that your parent was physically present in the United States for a longer period of time. In this case:
With only one U.S. citizen parent, you have a higher burden of proof in order to acquire your own U.S. citizenship. You will need to gather plenty of documentation to show your parent's more lengthy physical presence in the United States. Examples include school, employment and tax records, leases and deeds for a home, and affidavits from people with knowledge of your parent's U.S. residency.
Nevertheless, you yourself need not have lived in the U.S. at any time, nor met any other conditions to keep your citizenship.
If your parents were not married when you were born (you were born "out of wedlock"), you may be considered an "illegitimate" child for immigration purposes. If this applies to you, you will not be able to acquire citizenship through your father unless you have evidence showing that he "legitimated" you and established his paternity before you turned 18 years old.
Legitimation statutes for children born outside of marriage vary from country to country. The most common way for a father to legitimate his child is to:
In addition, your father must have taken steps to show that he assumed responsibility for your care while you were a minor child. You can provide evidence that he paid financial support for your care (either with a personal acknowledgement or by court order), that he married your mother shortly after your birth, that he "held himself out" to be your father to others, that he lived in the same home, or he took a DNA test to prove his paternity.
If you have read the information above and determined that you acquired U.S. citizenship at birth, you will likely want to apply for a Certificate of Citizenship. This is useful an official record of your status, and you can use it to apply for a U.S. passport. If you are over 18 years old, you should apply using Form N-600, Application for Certificate of Citizenship. (See Filling Out Form N-600 for help with this.)
If you are under 18 and you regularly reside abroad, but not because your parent is a member of the U.S. armed forces or government, your parent will need to file a different application on your behalf, Form N-600K, Application for Citizenship and Issuance of Certificate Under Section 322. Both are available on the Forms page of the USCIS website.