Most foreign-born adopted children acquire U.S. citizenship as soon as they enter the United States, thanks to the Child Citizenship Act of 2000 [PDF] (U.S. Citizenship and Immigration Services). Since the passage of the law, they do not need to formally apply but become citizens automatically. Adoptive parents of foreign-born children may obtain a citizenship certificate for their child, but will need to go through the application process to do so. Knowing in advance the kinds of documents that will be required and the sorts of delays and other administrative hurdles you'll face can help you plan for success.
This article focuses on the CCA and how it relates to foreign-born adoptees. See FindLaw's Citizenship section for additional articles and resources. Also, be aware that there are separate processes for foreign-born children of U.S. citizens.
In order for a foreign-born adopted child of U.S. parents to obtain automatic citizenship in accordance with the CCA, the applicant child:
Some foreign-born adopted children may need to wait until they have satisfied certain criteria before they automatically acquire citizenship. Still others (those living abroad) may need to formally apply to "naturalize," since the USCIS can't assume that an adoptee (or his/her parents) living abroad plans to live in the U.S. permanently.
Orphans adopted by a U.S. citizen parent are citizens once their adoption is final and they have lawfully entered the United States as permanent residents. Children who did not immigrate as orphans, but who were adopted by a U.S. citizen parent and obtained lawful permanent resident status also automatically acquire citizenship (so long as they meet all the criteria prior to their 18th birthday). Foreign children who are adopted by U.S. citizens who reside overseas are also entitled to citizenship, but under slightly different criteria. Such children may file for naturalization during a legal, temporary visit to the U.S. so long as they are under 18 and their parents or grandparents meet certain other eligibility criteria.
Adopted children residing in the United States may file for a certificate of citizenship using USCIS Form N-600. Adopted children residing outside the United States may file for naturalization using USCIS Form N-600K. A separate application must be filed, once naturalized, in order for the child to receive their U.S. passport.
It may seem as though acquiring citizenship for a child should be fairly quick and straightforward, but this couldn't be farther from the truth. Processes relating to citizenship are notoriously complicated and time consuming. Contact a local immigration law attorney to learn how they can help you make the appropriate arrangements.