Adoption was a legal institution of much importance in both of the classical nations of antiquity, whose laws frequently encouraged the possession of a large family. Adoption, in the stricter sense, in the Roman law, applied only to the case in which a person in the power of his father or grandfather was transferred to that of the person adopting him. Where the person adopted was already emancipated from the paternal power (patria potestas), and was regarded by the law as his own master (sui juris), the proceeding was called adrogation (adrogatio). At Athens, the adopted child was transferred from his own family and parish or tribe (dēmos), into those of the adoptive father, whose property he inherited in the absence of legitimate children, and whose sacred rights he was bound to maintain. In fact, the theory of adoption at Athens, as in India, was that there might be some one to offer the funeral cake, and prevent a failure of the funeral ceremonies. Only Athenian citizens could be adopted, so that not only the next of kin, but the whole community were interested in preventing fraudulent adoptions. With this view, registration in the demos of the adoptive father was requisite, in order to entitle the son to the rights of citizenship as a member of it.
In Rome, the adopted child assumed the name, and became bound to discharge the religious duties, of the adoptive father, which usually consisted in sacrifices to the penates or other divinities. Adoption was effected first by the form of a fictitious sale, and then under the authority of a magistrate, the prætor at Rome, or the governor (præses) in the provinces. Adrogation originally required a vote of the people in the Comitia Curiata; but under the emperors, it became the practice to effect it by an imperial rescript. This change of form made possible the adrogation of women. A patrician was sometimes adrogated into a plebeian family for political purposes. If a father, having children in his power, was adopted, both he and his children passed into the power of the adoptive father. It was requisite that the adoptive father should have no legitimate children at the time, and no reasonable prospect of having any. But the whole character and object of adoption were altered by the legislation of Justinian. Adoption was unknown to the early law of the Teutonic nations; but in the 15th century it became a prominent feature in the codes and social life of Prussia and Austria, and other German states. There, and also in France, the ceremony was carried through in open court, and conferred indefeasible rights of succession. It is, however, in the Hindu law that adoption is chiefly, in modern times, an active institution. Adoption has never existed as an institution either in England or Scotland. The patrimonial benefits of adoption may, however, be conferred by deed, as where a testator is said to place himself in loco parentis; but the express adoption of a child—e.g. as the result of the advertisement which frequently appears—imposes no legal liability, except under a contract with the true parent.
In the United States, adoption is regulated by the statutes of the several states. Generally, it is accomplished by mutual obligations, assumed in some form prescribed by law, binding upon the adopter to treat the one adopted as his own child, towards whom he will discharge all the duties of a parent; while the one adopted assumes all the obligations of a child towards a parent. But these laws differ in the several states, although they all aim at one result—viz. the creation of new civil relations of child and parent.