• A green card is a U.S. permanent residency document.liberty and flag image by zampa from Fotolia.com
  
  Eligible green card candidates file immigrant petitions with the U.S. Citizenship and Immigration Services (USCIS) prior to applying for a green card. In many cases, a U.S. citizen or permanent resident files the petition on behalf of the immigrant. Eligibility is determined individually, but requirements for a green card may include family relations in the U.S., employment and need for asylum.
  
  

General Eligibility

• Immigrants must provide an approved visa and be deemed "admissible" into the United States to qualify for a green card. According to the Immigration and Nationality Act, you may be inadmissible due to health issues, criminal activity or U.S. security concerns. Additionally, aliens requesting admission into the United States may be denied if they are likely to become a "public charge." Excluding special circumstances, undocumented aliens are considered inadmissible.
  
  

Family

• Immediate family members of U.S. citizens or permanent residents may apply for a green card. Immediate family may include parents, spouses, children, siblings and their families. Preference is shown for spouses, parents and unmarried children of U.S. citizens. Citizens applying for immigrant parents must be age 21 or older.
  
  

Employment

• Individuals may apply for a green card for employment purposes. Eligible employment may include a job offer within the United States, investment opportunities and skilled professions. According to the Department of Homeland Security, workers with exceptional and recognized abilities and individuals with advanced degrees are offered priority consideration.
  
  

Asylum and Refugee Status

• Refugees located within the United States when they claim asylum may choose to apply for a green card one year after being granted asylum status. However, individuals located outside of the U.S. requesting entry as a refugee are required by law to apply for a green card one year after admission into the U.S. as a refugee.
  
  

Diversity Program

• Every year the United States holds a "diversity lottery," offering 50,000 visas to individuals from qualifying countries seeking U.S. residency. Immigrants "winning" the lottery may receive or apply for a green card if they are admissible into the United States.
  
  

Other Circumstances

• Foreign national children born to U.S. military personnel may be eligible for a green card regardless of whether they are sponsored by a family member. Children born in the U.S. to foreign diplomats are not considered U.S. citizens, but they may receive a green card. Additionally, foreign nationals who served in the U.S. armed forces after October 15, 1978 are eligible for green cards.