Parental Kidnapping Prevention Act of 1979

Parental Kidnapping Act of 1979 - Requires appropriate State authorities to give full faith and credit to a child custody determination by a court of another State which has jurisdiction and meets specified conditions. Authorizes a State court with jurisdiction to modify a custody determination of another State court which no longer has or has declined to exercise jurisdiction.

Amends title IV (Child Support and Establishment of Paternity) of the Social Security Act to include as a function of the Parent Locator Service the provision of information to authorized persons about any absent parent or child for the enforcement of a child custody determination or with regard to parental kidnapping.

Prohibits the intentional restraint of a child in violation of any other persons' right of custody or visitation arising from: (1) a State custody determination; (2) a valid written agreement between the child's parents, foster parents, or guardians; or (3) a parental or guardian relationship.

Specifies (1) the jurisdictional basis for such offense, including the willful transportation of a child in interstate commerce, and (2) Federal investigation procedures.