In the United States, adoption is governed by state law, although state law must comply with overarching federal legislation. In general, the birthparent(s) sign(s) a consent to the adoption or a relinquishment of parental rights.

This consent or relinquishment is not legally binding prior to the birth of the child and can generally be revoked for a limited period of time after birth. The biological father of the child usually must be notified of any adoption plan, but procedures for this vary considerably. Separately, the prospective adoptive parents must file a petition to adopt. After a period of court supervision, usually six months to one year in length, during which the adoptive parents have custody of the child, the adoption is finalized. The adopted child then enjoys the legal footing in the family as a biological child.

Prospective adoptive parents must complete a home study before adopting, regardless of what kind of adoption is chosen. A homestudy is an in-depth application and interview process with a social worker that involves in-person interviews, reference checks, background checks, and home visits. The study is not standardized and may vary from state to state and agency to agency. The general regulations of the state of residence must be followed. The average home study usually takes three to six months to complete.

There are many variables that determine how long it will take to complete the adoption process such as whether or not pre-adoptive classes are required, the length of time to complete the homestudy and the length of time to identify a child for the family. On average, the adoption process may take one to two years.

The main ways to adopt are: adopt a child from the U.S. foster care system; adopt an infant in the United States; adopt a child from another country; or adopt a step-child(ren).

People seeking a healthy, U.S-born infant often enlist the help of an agency. Private agencies set criteria about whom they will serve, some more restrictive than others. In the past, those using an agency put their names on a list and waited for a match. Today, the agency is likely to send biographies of three or more sets of prospective adoptive parents to the birthparents, who pick the one they are most comfortable with. Then, the birthparents and adopting parents meet. At least half of the 15,000 or so domestic agency placements of infants each year involve such meetings. The child may be placed with the adopting parents immediately after birth or from foster care. If the process is closed, the adoptive parents may have to wait longer, since most agencies now encourage varying degrees of openness.

The other common way of adopting a domestic infant is by locating a birthmother, usually with a lawyer's help. Of the estimated 30,000 annual domestic infant adoptions, at least half are done independent of an agency. Independent adopters mail resumes to obstetricians and attorneys, advertise in newspaper classified sections, even create home pages on the Internet. The baby typically is taken home directly from the hospital. Adoptive and birthparents together arrange a plan for the adoption and ongoing contact, if desired.

In 2007, Americans adopted more than 19,292 children from other countries, usually young children from orphanages in developing nations of Asia, Eastern Europe, and Latin America.

Most intercountry placements are handled by U.S.-based agencies, which often facilitate adoptions in multiple countries, each with its own requirements governing who may adopt and who may be adopted. The placing organization abroad may be a governmental body, private orphanage, foundation, or other social welfare organization. Most countries require one or both of the adoptive parents to travel to the foreign country.

n 2005, more than 51,000 "waiting children" were adopted from the public foster care system in the United States. State agencies handle these adoptions, which typically happen in one of two ways: Families may apply directly to adopt a child in foster care, or first become foster parents and then adopt after the birthparents' rights are terminated.

Waiting children adopted in 2005 averaged seven years old. Most were deemed to have "special needs" because of physical, mental, or behavioral disabilities, age, or membership in a minority or sibling group.

Requirements for prospective adoptive parents vary depending on the type of adoption and agency involved (if applicable). In the United States, agency criteria for prospective adoptive parents are often more restrictive for infant adoptions than for adoptions of older children, because fewer infants are available. Many agencies set age limits for   prospective adoptive parents in infant adoptions, and birth parents may choose younger parents in independent adoptions arranged without agency involvement. In intercountry adoption, each country sets requirements that prospective adoptive parents must meet in order to be eligible to adopt. Adoptions of older children and intercountry adoptions may offer more flexibility for older prospective adoptive parents. If the adoption is done internationally or privately with an attorney or agency, parents are typically under 40, married for at least three years and financially stable.

The total cost of adoption varies depending upon a number of factors such as the type of adoption, the agency used, the state in which the adoptive parents reside, attorney fees and whether travel is required.

Range of Adoption Costs 
Foster Care Adoptions $0 - $2,500
Licensed Private Agency Adoptions $5,000 - $40,000+
Independent Adoptions $8,000 - $40,000+
Intercountry Adoptions $7,000 - $30,000