This was relatively uncommon until World War II, with only 6,000 adoption orders annually in the UK. This peaked at nearly 25,000 in 1968 as adoption became more socially acceptable, and the numbers of babies born to lone mothers rose in a climate hostile to single parenthood.

Adoption declined as the availability of babies fell with the introduction of the Abortion Act 1968, improving contraceptive services and increasing acceptability of single parenthood. However, with 10 per cent of couples suffering infertility, the demand continued, leading to the adoption of those previously perceived as difficult to place – i.e. physically, intellectually and/or emotionally disabled children and adolescents, those with terminal illness, and children of ethnic-minority groups.

Controversies regarding homosexual couples as adoptive parents, adoption of children with, or at high risk of, HIV/AIDS, transcultural adoption, and the increasing use of intercountry adoption to fulfil the needs of childless couples have provoked much consideration of the ethical dilemmas of adoption and its consequences for the children, their adoptive and birth families and society generally.

In the UK all adoptions (including interfamily and step-parent adoption) must take place through a registered adoption agency; this may be local authority based or provided by a registered voluntary agency. All local authorities must act as agencies, the voluntary agencies often providing specialist services to promote and support the adoption of more difficult-to-place children. Adoption orders cannot be granted until a child has resided with its proposed adopters for 13 weeks. In the case of newborn infants the mother cannot give formal consent to placement until the baby is six weeks old, although informal arrangements can be made before this time. In 2015, about 5,000 adoption orders were made in England.