State parentage laws, dictating who a newborn child’s first legal parents will be, have been the subject of constitutional challenges in several U.S. Supreme Court and many lower court decisions. All of those decisions, however, have focused on constitutional rights of adults (especially unwed biological fathers) who wish to become, or to avoid becoming, legal parents. Neither courts nor legal scholars have considered whether the children have any constitutional rights that constrain legislatures and courts in deciding which adults will be their legal parents. If a state enacted a parentage law that said, for example, that any child born to a birth mother who already had two children would be placed in a parent-child relationship at birth with applicants for adoption rather than with the birth mother, would that infringe on any constitutional right of the child? Or would the birth mother be the only person with standing to challenge the law? Such a law would be purely hypothetical in the U.S. (though not far from reality in some other parts of the world). But the actual current parentage laws in the United States, which confer legal parent status in almost all instances on biological parents, with no regard for fitness, also have a seriously adverse affect on a subset of children—specifically, children whose birth parents are manifestly unfit to raise children, as evidenced by serious child maltreatment histories, criminal records, substance abuse, mental illness, and/or imprisonment. This Article is the first to consider whether states violate a constitutional right of some children when their parentage laws consign the children to legal relationships with, and into the custody of, adults whom the state knows to be unfit. It identifies opportunities for children’s advocates to advance constitutional challenges to state parentage laws as applied to newborn offspring of adults unfit to parent, and it presents a robust legal theory to underwrite such challenges.