An orphanage is a residential institution, total institution or group home, devoted to the care of orphans and children who, for various reasons, cannot be cared for by their biological families. The parents may be deceased, absent, or abusive. There may be substance abuse or mental illness in the biological home, or the parent may simply be unwilling to care for the child. The legal responsibility for the support of abandoned children differs from country to country, and within countries. Government-run orphanages have been phased out in most developed countries during the latter half of the 20th century but continue to operate in many other regions internationally. It is now generally accepted that orphanages are detrimental to the emotional wellbeing of children, and government support goes instead towards supporting the family unit.

A few large international charities continue to fund orphanages, but most are still commonly founded by smaller charities and religious groups. Especially in developing countries, orphanages may prey on vulnerable families at risk of breakdown and actively recruit children to ensure continued funding. Orphanages in developing countries are rarely run by the state. However, not all orphanages that are state-run are less corrupted; the Romanian orphanages, like those in Bucharest, were founded due to the soaring population numbers catalyzed by dictator Nicolae Ceaușescu, who banned abortion and birth control and incentivized procreation in order to increase the Romanian workforce.

Today's residential institutions for children, also described as congregate care, include group homes, residential child care communities, children's homes, refuges, rehabilitation centers, night shelters, and youth treatment centers.

The Romans formed their first orphanages around 400 AD. Jewish law prescribed care for the widow and the orphan, and Athenian law supported all orphans of those killed in military service until the age of eighteen. Plato (Laws, 927) says: "Orphans should be placed under the care of public guardians. Men should have a fear of the loneliness of orphans and of the souls of their departed parents. A man should love the unfortunate orphan of whom he is guardian as if he were his own child. He should be as careful and as diligent in the management of the orphan's property as of his own or even more careful still." The care of orphans was referred to bishops and, during the Middle Ages, to monasteries. As soon as they were old enough, children were often given as apprentices to households to ensure their support and to learn an occupation.

In medieval Europe, care for orphans tended to reside with the Church. The Elizabethan Poor Laws were enacted at the time of the Reformation and placed public responsibility on individual parishes to care for the indigent poor.

The growth of sentimental philanthropy in the 18th century led to the establishment of the first charitable institutions that would cater to orphans. The Foundling Hospital was founded in 1741 by the philanthropic sea captain Thomas Coram in London, England, as a children's home for the "education and maintenance of exposed and deserted young children." The first children were admitted into a temporary house located in Hatton Garden. At first, no questions were asked about child or parent, but a distinguishing token was put on each child by the parent.

On reception, children were sent to wet nurses in the countryside, where they stayed until they were about four or five years old. At sixteen, girls were generally apprenticed as servants for four years; at fourteen, boys were apprenticed into a variety of occupations, typically for seven years. There was a small benevolent fund for adults.

In 1756, the House of Commons resolved that all children offered should be received, that local receiving places should be appointed all over the country, and that the funds should be publicly guaranteed. A basket was accordingly hung outside the hospital; the maximum age for admission was raised from two months to twelve, and a flood of children poured in from country workhouses. Parliament soon came to the conclusion that the indiscriminate admission should be discontinued. The hospital adopted a system of receiving children only with considerable sums. This practice was finally stopped in 1801, and it henceforth became a fundamental rule that no money was to be received.