To amend title 28 of the United States Code regarding enforcement of child custody orders.

Amends Federal judicial code provisions regarding full faith and credit given to child custody determinations to revise the definition of: (1) "contestant" to include a grandparent who claims a right to custody or visitation of a child, or in contested adoption cases, a person acting as a parent; and (2) "custody determination" to exclude a court order providing for visitation of a child and to include decrees, judgments, orders of adoption, and orders dismissing or denying petitions for adoption.

Modifies the definition of "home State" to include: (1) the State in which the child lived with a prospective adoptive parent or an agency with legal custody during a proceeding for adoption; (2) in the case of a child under six months old, the State in which the child lived from birth, or from soon after birth; and (3) in cases involving a proceeding for adoption, the State in which immediately preceding commencement of the proceeding, excluding periods of temporary absence, the child is in the custody of the prospective adoptive parent or parents, the child and the prospective adoptive parents are physically present and the prospective parents have lived for at least six months, and there is substantial evidence available concerning the child's present or future care.

Revises the definition of "modification" to apply to visitation determinations as well as custody determinations.

Defines "visitation determination" to mean a judgment, decree, or other court order providing for the visitation of a child, including a permanent and temporary order and initial order and modifications.

Extends specified requirements regarding child custody determinations to cover visitation determinations (for example, prohibitions against modifying another State's custody determinations also apply to visitation determinations).

Authorizes a court of a State to modify a custody determination made by a court of another State in an interstate contested adoption case in which the child has resided with the prospective adoptive parent for at least six consecutive months, if the court finds by clear and convincing evidence that the court of the other State failed to consider: (1) the extent of the detriment to the child in being moved from the child's custodial environment; (2) the nature of the relationship between the biological parents and the child and between the prospective parents and the child; and (3) the recommendation of the child's legal representative or guardian ad litem. Makes provisions enabling one State's court to modify a custody determination made by another State's court applicable only if the party seeking the new hearing has acted in good faith and has not abused or attempted to abuse the legal process.

Prohibits a State court from modifying a visitation determination made by a court of another State unless the court of the other State has declined to exercise jurisdiction to modify such determination.

Grants Federal district courts jurisdiction to determine which of conflicting State custody or visitation determinations is consistent with the provisions amended by this Act, or which of conflicting State courts is exercising jurisdiction consistently with such provisions.