The question of child custody comes up in the event of divorce. Parents who are planning to divorce would come to an agreement as to the question of custody of child/children i.e. whether the child will primarily live with them or, if not, what alternate arrangements could be made, such as visitation rights or shared parenting. Often the separating parents frame for themselves an arrangement specifying child custody rights with the help of their attorneys. If they are unable to reach a decision, the court may intervene and specify in the divorce decree with whom the divorcing couple’s children will live, keeping in mind the child’s best interests.

The custody of children can be physical, legal, joint or split. Generally, physical custody is awarded to one parent with whom the child will live most of the time. Legal custody, which includes the right to make decisions about the child’s religion, education, health, etc., is shared by both the custodial and non-custodial parents. In joint custody, the child spends equal amounts of time with both the parents. In split custody, the siblings are separated and each parent gets custody of one or more of the children. However, courts do not generally prefer to separate siblings.

Custody of the children born to unmarried parents is usually given to the mother. An unwed father does take priority over other relatives. Unlike divorcing couples, unmarried parents will not need to resolve any potentially complicated divorce-related issues such as division of property and payment of spousal support, so the decision-making process is focused almost exclusively on child custody, which is why resolution of custody and visitation may be more simplified for unmarried parents.

In some cases, people other than a child's parents may wish to obtain custody -- including relatives like grandparents, aunts, uncles, and close family friends. While some states label such a situation as "non-parental" or "third-party" custody, other states refer to the third-party's goal in these situations as obtaining "guardianship" of the child, rather than custody.

The guiding factor of the courts in deciding child custody cases is always the child’s “best interests”, which is in turn decided on the basis of which parent has been the child’s “primary caretaker”. “Best interests” includes preference of the children if they are old enough, age and sex of child, mental and physical health of the parents, religion and/or cultural considerations, support and opportunity for interaction with members of extended family of either parent, evidence of parental drug, and alcohol and sex abuse etc.

In a divorce decree, the non-custodial parent and other immediate relatives are allowed the right to visit the child, which is called visitation rights. This can be of two types: reasonable and fixed. Reasonable visitation is usually ordered, allowing the parents to exercise flexibility taking into consideration both the parents’ and children’s schedules. The parents have to cooperate and communicate frequently for the reasonable visitation approach to succeed. A court will be inclined to order a fixed schedule if the hostility between the parents is so severe that the need for regular contact between them may be detrimental to the child.