Citizens of the United States are allowed to sponsor their parents for US Green Cards and to sponsor your parents you must be above age 21. Moreover, you must also be willing to sponsor them financially. Though Green Card holders are allowed to sponsor their immediate relatives, they cannot sponsor their parents and only the US citizens are allowed to do so.
If you wish to sponsor your father or your mother who is living in a foreign country, you must first file Form I-130, for him or her. Along with other supporting documents and Form I-130, you must also submit your birth certificate. If you are a naturalized US citizen and if you are not a US citizen by birth, you must submit a copy of your naturalization certificate or a copy of your US passport. Remember that your birth certificate must contain the names of both your parents.
You need to file Form I-130, to sponsor your father who lives abroad and by whom you were not legitimated prior to your 18th birthday. Along with Form I-130, you should submit a copy of your birth certificate that contains your father’s name and you will have to submit copies of your naturalization certificate or your US passport, to demonstrate that you are a US citizen. In this case, you will have to submit supporting documents to prove that a relationship exits between you and your father.
If you were legitimated by your father, ahead of your 18th birthday, you need to file Form I-130, to sponsor your father for lawful status in America and you must submit the required supporting documents such as your United States passport, certificate of naturalization and your birth certificate, along with your petition. Apart from that, you must also submit documents to prove that you were legitimated by your father.
If your immigrant petition is approved, your parent who lives abroad will be required to visit the local US consulate to apply for an immigrant visa. If you wish to sponsor your father or mother who is already in the United States, he or she may file Form I-485 for adjustment of status, while you file Form I-130. Remember that separate petitions must be filed for each parent.