Certain guidelines determine whether or not one is eligible to obtain U.S. citizenship. They include: Age: applicant must be at least 18 years old; Residency: applicant must be a permanent resident and have resided in the U.S. continuously for the past three years; Good moral character: full disclosure of all facts pertaining to one's character is necessary, including an applicant's criminal history; Attachment to the Constitution: a demonstrated commitment to upholding the U.S. Constitution's principles; Language: the ability to read, write, and speak some English; U.S. Government and History knowledge: passage of the Immigration Test; Taking the Oath of Allegiance.