Over six million child combatants were killed or injured in the past decade. In this groundbreaking and comprehensive study, Singer, a fellow at the Brookings Institution and former adviser to the U.S. military, explores the rise and expansion of child soldiery. Children, Singer finds, enter armies and militias in numerous ways: as voluntary soldiers, indoctrinated to kill; as involuntary soldiers, forced into the militia or military by cruel adults; as child-terrorists; as members of all-child armies (such as the Hitler Youth); and as sexual slaves for superior officers. Singer (Corporate Warriors) explores different means of training and indoctrination, often through interviews with child-soldiers, as well as with adults who have fought against them and others who have tried to rehabilitate children forced into warfare. In the concluding section, Singer notes that instruments of international law such as the U.N. Convention on the Rights of the Child prohibit the use of child-combatants, but that these treaties have been ineffective in actually reducing the prevalence of child-soldiers. One hope is that the new International Criminal Court will be empowered to punish those who recruit children and send them into battle. However they seek to accomplish their goal, activists will be aided by the diligent research and reasoned analysis provided by Singer’s study, as will those who fund their work—i.e., anyone who gives to international aid organizations.