Parentage doctrines have proliferated, yet procedures to resolve the inevitable conflicts are lacking. Some states have priority rules, but the rankings are partial and rest on shallow reasoning. Recent trends favor the best interest of the child test, but it empowers judges to assess the pertinent values anew in each case. This chapter reconstructs American parentage law into a system of ordered rules to resolve parentage disputes with minimal ad hoc decision-making. Parentage law begins with the biological parent’s conditional liberty, reflected in the gestational presumption and the genetic petition or acknowledgment. Biological parents can also waive their childrearing liberty or forfeit it by not promptly and adequately raising the child. If there is only one legal or presumed parent, their parenting project can be shared with a partner through a second-parent adoption, acknowledgment of parentage, or preconception agreement. The parent may also seek caregiving help without sharing parenthood, but risks forfeiting their power to revoke this caregiving privilege if they share responsibility long enough for child and caregiver to develop rights and duties. The marital and residential presumptions are evidentiary inferences to the same biological, agreement, forfeiture, and caregiving grounds, so should be rebuttable only on the same basis.