The rule of law demands that States establish an appropriate minimum age of criminal responsibility (MACR) and guarantee effective procedural rights protection for children in conflict with the law. Based on case studies of the child justice systems of Sweden, Norway and the Netherlands, this chapter explores what an appropriate MACR requires in terms of procedural rights for children below and above the MACR. It is concluded that, even in supposedly progressive jurisdictions, there is still a world to win when it comes to safeguarding the rule of law and chidren´s rights protection in child justice.