Could I petition my parents to be US residents once I turn 21?

You should first decide if you should hire a lawyer or to do it for yourself. Either way, you will need to file I-130 petition for each parent once you turn 21 years old. Whether they can get a green cards in the US or have to travel to their country for their green cards depends on how they came to the US. If they entered without visas, they may have to go to their country to visa process or they might be able to remain here and apply for a waiver You will be able to file for your father if he married your mother before your 18th birthday and if so, for immigration purposes, CIS will recognize him as your father and hence, you can file for him as well.

I have some bad news for you: you cannot help your parents. Under the immigration law as it exists today, they cannot get green cards because they did not enter the U.S. legally. There might be an "immigration consultant" or even an attorney who will tell them to go back to their country so they could get green cards through the U.S. consul. Such an adviser is either ignorant of the law - or simply does not care about anything except getting paid for "handling" your case. The law is clear: if your parents leave the U.S., they will not come back for, at least, 10 years. The existing waivers of this 10-year bar do not apply to parents of U.S. citizens. So, don't get conned. As you likely heard, the President and the Congress are working on an immigration law reform. The new law might give people like your parents a way to become legal residents of this country. But the reform is no closer to be enacted today than it was a year ago. So you can wait for our elected representatives to complete their negotiations over the pork barrels that must be conceded in exchange for recognition of your parents' basic rights. Or you can try letting your congressman or senator know how you feel about this issue. Or, better yet, you might look around for a community group or organization that advocates for the immigration reform and join it. After all, this is the idea of citizenship - that changes to the better happen when we make them happen.

Yes, you can. I suggest that you contact an experienced immigration attorney for a face-to-face consultation and give him/her all of the facts surrounding your situation. He/she would then be in a better position to analyze your case, advise you of your options and, if possible, make sure that the necessary paperwork and documentation is presented so as not to delay the process.

Once you turn 21 you may petition for both. There will be issues regarding inadmissibility and they will probably have to consular process in the absence of immigration reform. If that is the case they will need waivers as well. I would suggest a meeting with a competent immigration attorney before you start the process.

Generally, a U.S. citizen son or daughter (who is 21 years or more of age) can petition for his/her parents. So in your case, you will be able to file the petition for your mother. You can also file a petition for your step father, if your step father and your mother were married before you turned 18 year old. However, because your parents entered the U.S. illegally, they would not be eligible to file adjustment of status applications (Greencard applications), in the U.S. (unless there was another petition filed for them prior to April 30, 2001, by a relative or an employer). If they don't have a prior petition (prior to April 30, 2001), they would have to do consular processing for immigrant visa, which means that they would have to leave the U.S. to process their immigrant visa in their home country. This however, would cause serious problems, because when they leave the U.S. (even for a day) for the immigrant visa interview, they would trigger the 10-year bar to reentry into the U.S. That is, the consulate would tell them that because their illegal presence in the U.S. of more than one year, they cannot return to the U.S. for 10 years (even if they have a approved relative petition filed by their son). Usually, a person can apply for a waiver of this 10-year illegal presence bar to reentry into the U.S. However, to file the waiver the person must show that if the waiver is not granted, it would cause "extreme and unusual" hardship to their qualifying U.S. citizen relative. The qualifying U.S. citizens for the purpose of the waiver are Spouses and Parents of the applicant, but NOT the children. That is, in the case of your parents, they would not be able to file a waiver application because you their child is not a qualifying relative for the waiver. So unless they have their parents (your grandparents) here in the U.S. as U.S. citizens or Permanent Residents, your parents would not be eligible to file the waiver application. Which would mean they wouldn't be able to return to the U.S. for 10 years. Unfortunately, even though you would be a U.S. citizen, at this point they won't be able to adjust status or do consular processing of immigrant visa (because of their ineligibility to even apply for a waiver). So in my view the best thing for you to do at this point is to wait for the immigration reform and see if something comes out of that.

If you were born in the US, you can file an I-130 visa petition for your parents when you turn 21. They should consult with an immigration attorney regarding what else they can do to become Lawful Permanent Residents.

If your parents came here without inspection, they cannot adjust status here. Consult with an attorney to see if they can do consulate processing with a waiver.