Child custody (also known as legal custody, conservatorship, or allocation of parenting time and responsibilities) refers to the legal possession, rights, and responsibilities for a minor child by the child’s birth or adoptive parents—including the right to make health care, religious, cultural, and education decisions about the child's upbringing.

During separation, and following divorce, a child’s natural parents often share custody of the child (shared custody or joint custody)—unless one or both of the child’s natural or adoptive parents are deemed to be unfit or pose a risk to the health, safety, and well-being of the child (the child’s best interests). If one of the parents is deemed unfit, the other parent may be awarded sole custody of the child.

In some cases a parent who is not allowed to have custody of a child may be given visitation rights—sometimes under the supervision of another adult (supervised visitation).

Child custody laws are usually located in your state’s statutes governing family and domestic matters, and may be referred to as the Family Code.

Child custody is distinct from guardianship of a child, which usually involves a relative or an unrelated person temporarily agreeing to take responsibility for a child following the death of the child’s birth or adoptive parents, or their abandonment. And adoption is taking full and permanent responsibility for a child by someone other than the child’s birth parents.

In Massachusetts, child custody laws are designed to ensure the best interests of the child are prioritized during and after the parents' separation or divorce. Custody can be categorized as legal custody, which involves the right to make major decisions about the child's welfare, and physical custody, which pertains to where the child will live. Massachusetts courts may grant joint legal custody, allowing both parents to make decisions for the child, or sole legal custody to one parent if the other is deemed unfit. Similarly, joint physical custody can be awarded, or sole physical custody if it serves the child's best interests. When one parent is awarded sole custody, the non-custodial parent may receive visitation rights, which can be supervised if necessary to protect the child's safety. These laws are found in the Massachusetts General Laws under the sections dealing with domestic relations and family law. It's important to distinguish child custody from guardianship, which is a temporary arrangement typically made when parents are unable to care for their child, and from adoption, which is a permanent legal transfer of all parental rights to another individual or couple.