Can a grandson of a US Citizen apply for US Citizenship?

Question

The mother applied for herself but was denied because she didn't have Marriage Certificate of her parents. She only had her Birth Certificate to show.

Answer 1

Request for the issuance of the marriage certificate or any other proof of filiation so that the grandson can be petitioned as a US citizen by the grandmother.

Answer 2

Yes.

Her parents can get COM.

Answer 3

This issue is more complicated than the other answers make it appear.  Here is an official reference:

http://travel.state.gov/family/adoption/...

As you can see, the child's parent must be a US citizen in order for the child to win expeditious naturalization (not citizenship from birth) through a grandparent's residence in the US.  And the child must apply before age 18.

Otherwise, a grandparent cannot petition for a grandchild.