Children are always among the victims and sometimes also among some responsible when war crimes, crimes against humanity or genocide are committed. This study assesses how different international criminal jurisdictions have considered international crimes committed against or by children. It presents the legal standards pertaining to the protection of children victims of international crimes, as well as of children who allegedly participated in such crimes. It assesses the extent to which several international and hybrid courts have dealt with crimes committed against children, going back in time to the International Military Tribunals of Nuremberg and Tokyo, and then surveying more recent jurisdictions, namely the United Nations-established International Criminal Tribunals for the former Yugoslavia and for Rwanda, the Special Court for Sierra Leone, and the International Criminal Court. It proposes an agenda for improvement, with specific recommendations to expand the contributions of international justice for children.