Is it possible to adopt an adult mexican citizen to make them legal in the US?

There is no immigration benefit provided to adopted adults. If an adoption of a child is done properly and certain requirements are met, then the adopted child is eligible for US citizenship, but there is no corresponding benefit for adopted adults. Joyce Schwensen DISCLAIMER: This answer does not constitute legal advice nor does it form an attorney-client relationship between the questioner and responder. You should seek competent legal counsel in your jurisdiction to address any specific legal concerns you have.

It is not possible to adopt someone above 18 (for orphans) and 16 for non orphans. You might want to talk to a good immigration lawyer about other options. Good Luck Shah Peerally Founder and Managing Attorney of Shah Peerally Law Group PC The Law Firm Deals in Immigration law & Debt Settlement Negotiations. Note: The above answer is provided for informational use only. One should not act or refrain to act solely based on the information provided. No attorney client relationship is created unless a retainer or a fee agreement is signed by the attorney and the client