After a child is placed with you, you must fulfill the legal requirements for adoption. Hiring an attorney may be necessary at this time, if you have not already retained one.
Usually a child lives with the adoptive family for at least six months before the adoption is finalized legally, although this period varies according to state law -- unlike some intercountry adoptions, however, where the adoption is completed before the child leaves her country. During this time before the adoption is finalized, the agency will provide supportive services. The social worker may visit several times to ensure that the child is well cared for and to write up the required court reports. After this period, the agency will submit a written recommendation of adoption approval to the court, and you or your attorney can then file with the court to complete the adoption.
For intercountry adoptions, finalization of the adoption depends on the type of visa the child has and the laws in your state. The actual adoption procedure is just one of a series of legal processes required for intercountry adoption. You must also fulfill the U.S. Immigration and Naturalization Service's requirements and then proceed to naturalize your child as a citizen of the United States.
Source: National Adoption Information Clearinghouse