How to Become a U.S. Citizen Are you are a green card holder? You may be eligible to apply to become a U.S. citizen. You will need a length of residency in the U.S., knowledge of the U.S. government, and a willingness to swear allegiance to the country. English language skills are generally required, but can be waived in certain circumstances. Find out what exactly is required to become a U.S. citizen.