Evidence about the development of adoptees can be supported in newer studies. It can be said that adoptees, in some respect, tend to develop differently from the general population. This can be seen in many aspects of life, but usually can be found as a greater risk around the time of adolescence. For example, it has been found that many adoptees experience difficulty in establishing a sense of identity.[126]
Adoptions can occur either between related family members, or unrelated individuals. Historically, most adoptions occurred within a family. The most recent data from the U.S. indicates about half of adoptions are currently between related individuals.[78] A common example of this is a "stepparent adoption", where the new partner of a parent may legally adopt a child from the parent's previous relationship. Intra-family adoption can also occur through surrender, as a result of parental death, or when the child cannot otherwise be cared for and a family member agrees to take over.

In the 1970s, as adoption search and support organizations developed, there were challenges to the language in common use at the time. As books like Adoption Triangle by Sorosky, Pannor and Baran were published, and support groups formed like CUB (Concerned United Birthparents), a major shift from "natural parent" to "birthparent"[182][183] occurred. Along with the change in times and social attitudes came additional examination of the language used in adoption.
The American model of adoption eventually proliferated globally. England and Wales established their first formal adoption law in 1926. The Netherlands passed its law in 1956. Sweden made adoptees full members of the family in 1959. West Germany enacted its first laws in 1977.[49] Additionally, the Asian powers opened their orphanage systems to adoption, influenced as they were by Western ideas following colonial rule and military occupation.[50] In France, local public institutions accredit candidates for adoption, who can then contact orphanages abroad, or ask for the support of NGOs. The system does not involve fees, but gives considerable power to social workers whose decisions may restrict adoption to standardized families (middle-age, medium to high income, heterosexual, Caucasian).[51]

In some countries, such as the United States, "Homecoming Day" is the day when an adoptee is officially united with their new adoptive family.[196] In some adoptive families, this day marks an especially important event and is celebrated annually from thereafter. The term Gotcha Day is also used to refer to this day. Many adopted people and birth parents find this term to be offensive.
International adoption: involves the placing of a child for adoption outside that child's country of birth. This can occur through both public and private agencies. In some countries, such as Sweden, these adoptions account for the majority of cases (see above Table). The U.S. example, however, indicates there is wide variation by country since adoptions from abroad account for less than 15% of its cases.[83] More than 60,000 Russian children have been adopted in the United States since 1992,[85] and a similar number of Chinese children were adopted from 1995 to 2005.[86] The laws of different countries vary in their willingness to allow international adoptions. Recognizing the difficulties and challenges associated with international adoption, and in an effort to protect those involved from the corruption and exploitation which sometimes accompanies it, the Hague Conference on Private International Law developed the Hague Adoption Convention, which came into force on 1 May 1995 and has been ratified by 85 countries as of November 2011.[87]
Social workers and other professionals in the field of adoption began changing terms of use to reflect what was being expressed by the parties involved. In 1979, Marietta Spencer wrote "The Terminology of Adoption" for The Child Welfare League of America (CWLA),[184] which was the basis for her later work "Constructive Adoption Terminology".[185] This influenced Pat Johnston's "Positive Adoption Language" (PAL) and "Respectful Adoption Language" (RAL).[186] The terms contained in "Positive Adoption Language" include the terms "birth mother" (to replace the terms "natural mother" and "real mother"), and "placing" (to replace the term "surrender"). These kinds of recommendations encouraged people to be more aware of their use of adoption terminology.
Nevertheless, work on adult adoptees has found that the additional risks faced by adoptees are largely confined to adolescence. Young adult adoptees were shown to be alike with adults from biological families and scored better than adults raised in alternative family types including single parent and step-families.[137] Moreover, while adult adoptees showed more variability than their non-adopted peers on a range of psychosocial measures, adult adoptees exhibited more similarities than differences with adults who had not been adopted.[138] There have been many cases of remediation or the reversibility of early trauma. For example, in one of the earliest studies conducted, Professor Goldfarb in England concluded that some children adjust well socially and emotionally despite their negative experiences of institutional deprivation in early childhood.[139] Other researchers also found that prolonged institutionalization does not necessarily lead to emotional problems or character defects in all children. This suggests that there will always be some children who fare well, who are resilient, regardless of their experiences in early childhood.[140] Furthermore, much of the research on psychological outcomes for adoptees draws from clinical populations. This suggests that conclusions such that adoptees are more likely to have behavioral problems such as ODD and ADHD may be biased. Since the proportion of adoptees that seek mental health treatment is small, psychological outcomes for adoptees compared to those for the general population are more similar than some researchers propose.[141]
Beyond the foundational issues, the unique questions posed for adoptive parents are varied. They include how to respond to stereotypes, answering questions about heritage, and how best to maintain connections with biological kin when in an open adoption.[97] One author suggests a common question adoptive parents have is: "Will we love the child even though he/she is not our biological child?"[98] A specific concern for many parents is accommodating an adoptee in the classroom.[99] Familiar lessons like "draw your family tree" or "trace your eye color back through your parents and grandparents to see where your genes come from" could be hurtful to children who were adopted and do not know this biological information. Numerous suggestions have been made to substitute new lessons, e.g., focusing on "family orchards."[100]
Other ancient civilizations, notably India and China, used some form of adoption as well. Evidence suggests the goal of this practice was to ensure the continuity of cultural and religious practices; in contrast to the Western idea of extending family lines. In ancient India, secondary sonship, clearly denounced by the Rigveda,[12] continued, in a limited and highly ritualistic form, so that an adopter might have the necessary funerary rites performed by a son.[13] China had a similar idea of adoption with males adopted solely to perform the duties of ancestor worship.[14]
The most recent adoption attitudes survey completed by the Evan Donaldson Institute provides further evidence of this stigma. Nearly one-third of the surveyed population believed adoptees are less-well adjusted, more prone to medical issues, and predisposed to drug and alcohol problems. Additionally, 40–45% thought adoptees were more likely to have behavior problems and trouble at school. In contrast, the same study indicated adoptive parents were viewed favorably, with nearly 90% describing them as "lucky, advantaged, and unselfish."[144]
Attitudes and laws regarding adoption vary greatly. Whereas all cultures make arrangements whereby children whose birth parents are unavailable to rear them can be brought up by others, not all cultures have the concept of adoption, that is treating unrelated children as equivalent to biological children of the adoptive parents. Under Islamic Law, for example, adopted children must keep their original surname to be identified with blood relations,[194] and, traditionally, women wear a hijab in the presence of males in their adoptive households. In Egypt, these cultural distinctions have led to making adoption illegal.[195]

The number of adoptions in the United States peaked in 1970.[45] It is uncertain what caused the subsequent decline. Likely contributing factors in the 1960s and 1970s include a decline in the fertility rate, associated with the introduction of the pill, the completion of legalization of artificial birth control methods, the introduction of federal funding to make family planning services available to the young and low income, and the legalization of abortion. In addition, the years of the late 1960s and early 1970s saw a dramatic change in society's view of illegitimacy and in the legal rights[46] of those born outside of wedlock. In response, family preservation efforts grew[47] so that few children born out of wedlock today are adopted. Ironically, adoption is far more visible and discussed in society today, yet it is less common.[48]
Adoption is the legal process through which a child joins a family different from his or her birth parents. Adoption is a permanent, lifelong commitment to a child. In CPS cases, adoption becomes an option if CPS and the child's birth parents cannot resolve issues that made it unsafe for the child to live at home. Then, CPS may ask the court to end the parents' rights to the child and place the child with another family permanently. A child can also become legally free for adoption if both birth parents agree to give up their parental rights.

Unlike guardianship or other systems designed for the care of the young, adoption is intended to effect a permanent change in status and as such requires societal recognition, either through legal or religious sanction. Historically, some societies have enacted specific laws governing adoption; where others have tried to achieve adoption through less formal means, notably via contracts that specified inheritance rights and parental responsibilities without an accompanying transfer of filiation. Modern systems of adoption, arising in the 20th century, tend to be governed by comprehensive statutes and regulations.