What are the requirements for citizenship in the United States?
A person may become a U.S. citizen either through birth or through naturalization.
The requirements for naturalization are fairly extensive. In general, they require that one be a lawfully admitted resident of the United States, be of good moral character, show attachment to the principles of the Constitution, and demonstrate a knowledge and understanding of the fundamentals of the history of the form of government of the United States.
The entire list of details as well as U.S. history study guides and information on how to be sent naturalization forms can be accessed at the United States Citizenship and Immigration Services website.
—The Fact Monster