friend was brought to the US illegally as a child. How can he become a citizen?

Currently he can't. Unless they pass something like the DREAM act legislation. And it doesn't look too likely that that will happen soon.

If he is under 18 years old he is not responsible for being illegally in the US as he is not an adult. If he returns to his home country where he is a citizen before he is 18.5 he won't have any ban for reentering the US and can try to immigrate using legal means.

If he is older than 19 years old he will have a 10 year ban on reentry as soon as he leaves the US.Even if you would marry him he would have to return to his home country, apply and manage to get a waiver of inadmissibility before he could come back.

He can't become a citizen if he is here illegally while in this country. Like everyone else in the world that wants to live in the US legally, he must begin the process in his home country at a US embassy or consulate abroad. Can't do it here.

It's unfortunate that his parents put him in that situation, but they should have thought about the long term consequences and potential destruction it could cause on the lives of their children before they made such a foolish and irresponsible mistake.

So he has until he is 18 year and 6 months old to return to his home country, and apply for a visa. If he chooses to remain, he will postpone the inevitable and risk a 3 year ban on entering the US. If he states until he is 20, there will be a 10 year ban.

That's it, rules are rules, law is law.

Whil he is still illegal in the USA he will NEVER become a US citizen

He must go back home - who cares that he doesnt know anyone there. Wherever he was born - THAT is HIS country. The USA is NOT his country.

Assuming he is an adult - when he leaves USA he will be BANNED from entering the USA again for 10 years. ALL illegals are banned when they leave USA - that is their punishment for being illegal.

He can blame his MOTHER for screwing up his life.

He can't. citizenship comes after being a LEGAL resident for 5 years. If he entered the country illegally,he has to return to his home country and apply to come back legally. He cannot gain legal status while he is living here illegally.

This is a very difficult situation since he doesn't have any relatives that are citizens. He might have to get married to a US citizen out side the US so that they wont notice that he was here Illegally in the first place otherwise if he gets married here he will have to pay a forgiveness citation it used to be of 1,000 dollars and that was it, but now he will have to pay the citation and exit the country and it can take up to 10 years for him to come back. I really hope for an immigration reform for people like your friend, they need to get legalize.

An illegal cannot adjust status in the US

Marriage and babies will not help either ..that is a myth

To become legal you have to return home

There is a specialty forum one that deals solely with your unique issue. http://immigrate2us.net/

He needs to go back where he was born and apply from there.