Refugees and qualifying spouses and children of refugees should apply for permanent residency within one year of entering the United States, according to the U.S. Citizenship and Immigration Services. Parents and spouses of U.S. citizens can also apply for permanent residency, and they receive high priority.
Foreign nationals can also apply for permanent residency if they are sons or daughters of a U.S. citizen or permanent resident, says the USCIS. Unmarried, adult children of citizens receive preference in this group. Those seeking permanent residency based on employment may apply as well. Priority in this group goes to those with extraordinary talents, outstanding researchers and certain business executives.