Since ancient times and in all human cultures, children have been transferred from adults who would not or could not be parents to adults who wanted them for love, labor, and property. Adoption’s close association with humanitarianism, upward mobility, and infertility, however, are uniquely modern phenomena. An especially prominent feature of modern adoption history has been matching: the idea that adoption substituted one family for another so carefully, systematically, and completely that natal kinship was rendered invisible and irrelevant. This notion was unusual in the history of family formation, especially because the most obvious thing about adoption has been that it is a different way to make a family. Practices that aimed to hide this difference ironically made modern adoption most distinctive.

In the United States, state legislatures began passing adoption laws in the nineteenth-century. The Massachusetts Adoption of Children Act, enacted in 1851, is widely considered the first “modern” adoption law. Adoption reform in other western industrial nations lagged. England, for example, did not pass adoption legislation until 1926. Observers have frequently attributed the acceptance of adoption in the United States to its compatibility with cherished national traditions, from immigration to democracy. According to this way of thinking, solidarities achieved on purpose are more powerful—and more quintessentially American—than solidarities ascribed to blood. Yet adoption has always had a symbolic importance that outstripped its statistical significance. Adoption has touched only a small minority of children and adults while telling stories about identity and belonging that include us all.

During the twentieth century, numbers of adoptions increased dramatically in the United States. In 1900, formalizing adoptive kinship in a court was still very rare. By 1970, the numerical peak of twentieth-century adoption, 175,000 adoptions were finalized annually. “Stranger” or “non-relative” adoptions have predominated over time, and most people equate adoption with families in which parents and children lack genetic ties. Today, however, a majority of children are adopted by natal relatives and step-parents, a development that corresponds to the rise of divorce, remarriage, and long-term cohabitation.

Conservative estimates (which do not include informal adoptions) suggest that five million Americans alive today are adoptees, 2-4 percent of all families have adopted, and 2.5 percent of all children under 18 are adopted. Accurate historical statistics about twentieth-century adoption are, unfortunately, almost impossible to locate. A national reporting system existed for only thirty years (from 1945 to 1975) and even during this period, data was supplied by states and territories on a purely voluntary basis.

We do know that adoptive kinship is not typical. Families touched by adoption are significantly more racially diverse, better educated, and more affluent than families in general. We know this because in 2000, “adopted son/daughter” was included as a census category for the first time in U.S. history.

Since World War II, adoption has clearly globalized. From Germany in the 1940s and Korea in the 1950s to China and Guatemala today, countries that export children for adoption have been devastated by poverty, war, and genocide. Because growing numbers of adoptions are transracial and/or international, many of today’s adoptive families have literally made adoption more visible than it was in the past. But total numbers of adoptions have actually declined since 1970. In recent years, approximately 125,000 children have been adopted annually by strangers and relatives in the United States.

Modern adoption history has been marked by vigorous reforms dedicated to surrounding child placement with legal and scientific safeguards enforced by trained professionals working under the auspices of certified agencies. In 1917, for instance, Minnesota passed the first state law that required children and adults to be investigated and adoption records to be shielded from public view. By midcentury, virtually all states in the country had revised their laws to incorporate such minimum standards as pre-placement inquiry, post-placement probation, and confidentiality and sealed records. At their best, these standards promoted child welfare. Yet they also reflected eugenic anxieties about the quality of adoptable children and served to make adult tastes and preferences more influential in adoption than children’s needs.

Since 1950, a number of major shifts have occurred. First, “adoptability” expanded beyond “normal” children to include older, disabled, non-white, and other children with special needs. Since 1970, earlier reforms guaranteeing confidentiality and sealed records have been forcefully criticized and movements to encourage search, reunion, and “open adoption” have mobilized sympathy and support. The adoption closet has been replaced by an astonishing variety of adoption communities and communications. Adoption is visible in popular culture, grassroots organizations, politics, daily media, and on the internet.

Adoption history illustrates that public and private issues are inseparable. Ideas about blood and belonging, nature and nurture, needs and rights are not the exclusive products of individual choices and personal freedoms. They have been decisively shaped by law and public policy and cultural change, which in turn have altered Americans’ ordinary lives and the families in which they live and love.