This Article examines the legal and policy implications that arise when a state that expressly prohibits recognition or enforcement of any rights arising from a same-sex relationship is confronted with a request to register and enforce a child custody order issued by another state that gives custody or visitation rights to a biological mother’s former same-sex partner. As more states confer marital rights to same-sex couples, this issue will occur with increasing frequency. The first reported case in the nation to address the issue, Miller-Jenkins v. Miller-Jenkins, has garnered attention from the national media, including a cover story in the Washington Post Magazine and, most recently, a feature story in Newsweek Magazine. The underlying issue arises from two seemingly conflicting federal statutes, both passed pursuant to Congress’s authority to prescribe what effect, if any, a foreign judgment should have in another state. In 1980, Congress passed the federal Parental Kidnapping Prevention Act (PKPA), which requires a receiving state to give full faith and credit to another state’s custody or visitation order. In 1996, however, Congress passed the federal Defense of Marriage Act (DOMA), which expressly recognizes the right of each state to refuse to give full faith and credit to any orders arising out of same-sex relationships treated as marriage. Thus, when a court in Vermont, Massachusetts, California, or New Jersey (to name a few) declares a woman to be a parent to her former same-sex partner’s biological child and grants a visitation or custody order in her favor when the relationship between the women ends, are other states required to give the order full faith and credit as a result of the PKPA, or can states refuse to give it full faith and credit pursuant to DOMA? This Article discusses the various arguments raised on both sides of the issue in the context of the Miller-Jenkins litigation. It then articulates a workable standard for interstate custody disputes arising out of same-sex relationships that gives proper respect to the constitutional mandate to give full faith and credit to sister state judgments while preserving state sovereignty over core domestic relations matters.