This Article argues that a father’s biological connection to a child is constitutionally significant principally because it evidences the consent of the biological mother to the father’s parental relationship with the child. The biological mother’s consent is critical because she is the initial “constitutional parent.” Her constitutional parental rights arise from her role nourishing the child in her womb and enduring the pain and danger of childbirth. This labor gives her a constitutionally protected voice in the child’s upbringing including a right to decide generally who else shall be allowed to develop a parental relationship with the child. Only if the father himself sufficiently labors in developing a functional parental relationship with the child prior to the mother’s withdrawal of her consent to his co-parenting will the Constitution protect his relationship with the child. This “labor-with-consent” theory of constitutional parental rights also should be applied to the claims for constitutional protection of parental rights by functional parents, egg donors, gestational surrogate mothers, and intended parents.