Should your evidence and petition to the USCIS succeed in proving that you are indeed a person of extraordinary ability, the O-1 can be approved for a maximum of three years at a time. You will be allowed to apply for unlimited extensions should you be able to provide additional evidence of upcoming events or employment. However, O-1 visas are not always approved for three years. When a person applies for an O-1 visa, the validity dates-meaning the period the recipient is allowed to stay in the U.S.-are set around the specific period of time that is required to perform or participate in a certain event or events. If you have only one short event or project in which you wish to participate, then the USCIS will approve your O-1 visa to cover only this time period.