If the adoption was finalized in the foreign country and the child has been issued an IR-3 visa, citizenship automatically confers when the child legally enters the United States. If the adoption was not finalized abroad and the child was issued an IR-4 visa (which requires parents to adopt or re-adopt the child in the United States), citizenship confers instantly on the day the adoption is finalized in the United States.http://international.adoption.com/foreign/citizenship-for-your-internationally-adopted-child.html