This book is based on a dissertation which was defended at the University of Hamburg on the 4th of October 2016. First of all, I would like to thank my supervisor, Prof. Dr. Florian Je?berger, for his invaluable support. His encouragement and keen interest in this project have provided me with a continuous source of motivation throughout the writing process. Secondly, I would like to thank Prof. Dr. Gerhard Werle for his helpful feedback and suggestions at the final stage of this project. I would further like to thank my professors at Columbia Law School, whom I have had the privilege to meet during my LL.M. studies in 2013/2014. These are: Prof. Robert Ferguson, who has shaped my way of thinking about punishment and restorative justice; Prof. Graeme Simpson, from whom I have learned so much about transitional justice; Prof. Katherine Franke, who helped me to explore the gendered dimensions of child soldiering; and Prof. Jane Spinak, who challenged me to move from theory to practice. I also thank Radhika Coomaraswamy, who shared with us her experiences as the former SRSG on Children and Armed Conflict during her seminar on Children and Armed Conflict at NYU Law School. I am indebted to Virginie Ladisch and Rachel Goodman from the Children and Youth Program of the International Center for Transitional Justice, with whom I was able to discuss my ideas and who have helped me greatly in developing them further. I thank the Friedrich Naumann Foundation for Liberty for the financial support, enabling the writing of the dissertation which led to this book. Lastly, I take this opportunity to thank my parents and my partner Jakob for everything, but especially for their love, encouragement, and support.