The first step toward applying for naturalization to become a U.S. citizen is to determine whether all qualifications have been met. Eligibility standards vary depending on the situation of the applicant. USCIS offers an eligibility worksheet that might help some applicants determine whether they meet requirements, but it does not help those who are under the age of 18 and many of those applying in connection with service of themselves or a spouse in the U.S. armed services.
For most applicants, qualifications include being at least 18-years-old and holding status as a lawful permanent resident of the U.S. for a certain period. The length of time varies between three to five years for most applicants. In addition, the applicant must fulfill local residency requirements and not have spent too much time traveling abroad in the years before applying. A Wheaton citizenship/naturalization lawyer could help ascertain the requirements that pertain to a particular situation.