In many cases children are adopted by relatives. Many states now permit adoption by unmarried adults; some allow adoption by homosexual couples. Most adoptions are of the same race. Transracial adoptions are controversial, pitting issues of culture and heritage against the need of a child for a stable parent-child relationship as early in life as possible, regardless of race. The Multiethnic Placement Act (1994) made it illegal for U.S. states to hold up adoptions solely in order to match racial or ethnic background of the child.

In adoption by unrelated adults, the courts have traditionally attempted to ease adjustment to the adoptive family and protect the privacy of the (often unwed) mother by maintaining secrecy regarding the child's birth parents. Since the 1970s, however, a growing number of adopted children have attempted to identify their birth parents, and "open adoption," in which adoptive and birth parents maintain a relationship, has become more accepted. Questions of parental rights and where these stand vis-à-vis the rights and best interests of the child have also been highlighted in cases in which the courts tranferred custody of adopted or fostered children to birth parents who had previously given them up.

Many children are adopted through public or private agencies, but a growing number are adopted through private placement, in which the prospective adoptive parents advertise for or are otherwise put into contact with a birth mother, usually with the help of a lawyer who is familiar with the process and the legal requirements of the individual states. As birth control and abortion have become more available and as the stigma formerly attached to unwed motherhood has lifted, fewer infants have been put up for adoption, making it increasingly difficult for prospective parents to find young children to adopt (see also infertility). In many cases, parents have adopted babies from outside the United States, particularly South Korea, and Mexico and other Latin American countries, but the increased demand has also been accompanied by black-market adoption arrangements. In 1980 the U.S. Congress passed the Adoption Assistance and Child Welfare Act to give support to foster families who adopt and to families who adopt children with disabilities.

See also foster care, guardian and ward.