To obtain a U.S. green card, a noncitizen must become a permanent resident of the United States, according to the U.S. Department of Homeland Security. A green card is proof of permanent U.S. residency for a noncitizen who is authorized to reside and work in the United States.
There are different steps a noncitizen must take to apply for a green card, depending on the category of eligibility in which he falls, explains U.S. Citizenship and Immigration Services. To qualify for U.S. residency, a noncitizen must be sponsored through family members or an employer. Some immigrants may be eligible to apply as refugees or through asylum status. Additionally, some special circumstances may qualify applicants for a green card through programs such as a K Nonimmigrant for fiancé petition, the Diversity Immigration Visa Program, Special Immigrant Juvenile Status and the Legal Immigration Family Equity Act.
Once eligibility has been determined, a noncitizen who has been admitted into the United States through an approved visa may apply for an adjustment of status to permanent resident, according to U.S. Citizenship and Immigration Services. An immigrant who has not yet been admitted into the United States may obtain a green card through a method called consular processing. In either case, the immigrant must be granted a visa before he can apply for a green card.