Child abandonment is the practice of relinquishing interests and claims over one's offspring in an illegal way, with the intent of never resuming or reasserting guardianship. The phrase is typically used to describe the physical abandonment of a child. Still, it can also include severe cases of neglect and emotional abandonment, such as when parents fail to provide financial and emotional support for children over an extended period (sometimes referred to as "throwaway" children). An abandoned child is referred to as a foundling (as opposed to a runaway or an orphan). Baby dumping refers to parents leaving a child younger than 12 months in a public or private place with the intent of terminating their care for the child. It is also known as rehoming when adoptive parents use illegal means, such as the internet, to find new homes for their children. In the case where child abandonment is anonymous within the first 12 months, it may be referred to as secret child abandonment.

In the United States and many other countries, child abandonment is usually treated as a subset of the broader category of child abuse. (However, all 50 states and D.C. have laws allowing a parent to permanently surrender a child at a designated safe haven "where they will not be prosecuted.") In the United States it is punishable as a class 4 felony, and a second or subsequent offense after a prior conviction is a class 3 felony (see classes of felonies) with different state judicial systems treating it with varying severities and classifications. Child abandonment may lead to the permanent loss of parental rights of the parents. Some states allow for reinstatement of the parental rights, with about half of the states in the US having had laws for this purpose. Perpetrators can also be charged with reckless abandonment if victims die as a result of their actions or neglect.

Official statistics on child abandonment do not exist in most countries. In Denmark, an estimate of child abandonment prevalence was 1.7 infants per 100,000 births, with another source suggesting higher prevalence in Central and Eastern European countries such as Slovakia with data suggesting 4.9 per 1,000 live births.

In 2015, the United States' government spent over $9 billion to support 427,910 children who were in foster care.

Child abandonment is illegal in most of the world, and depending upon the facts of the case and laws of the state in which it occurs could be prosecuted as a misdemeanor or felony criminal offense.

Historically, many cultures practiced abandonment of infants, often called "infant exposure." Children were left on hillsides, in the wilderness, near churches, and in other public places. If taken up by others, the children might join another family either as slaves or as free family members. Roman societies, in particular, chose slaves to raise their children rather than family members, who were often indifferent towards their children. Although being found by others would allow children who were abandoned to often survive, exposure is sometimes compared to infanticide—as described by Tertullian in his Apology: "it is certainly the more cruel way to kill... by exposure to cold and hunger and dogs." Despite the comparison, other sources report that infanticide and exposure were viewed as morally different in ancient times.

In the Early Middle Ages, parents who did not want to raise their children gave them to monasteries with a small fee, an act known as oblation, and in times of social stress, monasteries often received large numbers of children. By the high Middle Ages, oblation was less common and more often arranged privately between the monastery and the parents of the child. Sometimes, medieval hospitals cared for abandoned children at the community's expense. Still, some refused to do so because being willing to accept abandoned children would increase abandonment rates. Medieval laws in Europe governing child abandonment, as the Visigothic Code, often prescribed that the person who had taken up the child was entitled to the child's service as a slave. Conscripting or enslaving children into armies and labor pools often occurred as a consequence of war or pestilence when many children were left parentless. Abandoned children then became the wards of the state, military organization, or religious group. When this practice happened en masse, it had the advantage of ensuring the strength and continuity of cultural and religious practices in medieval society.

Early Modern Europe saw the rise of foundling homes and increased abandonment of children to these homes. These numbers continued to rise and peaked when 5% of all births resulted in abandonment in France around 1830. The national reaction to this was to limit the resources provided by foundling homes and switch to foster homes instead such that fewer children would die within overcrowded foundling homes during infancy. As access to contraception increased and economic conditions improved in Europe towards the end of the 19th century, the number of children being abandoned declined.