Over 4,500 children were detained in Rwanda in 1998, most accused of participating in the genocide. This chapter introduces the issue of children accused of committing genocidal acts, but also more broadly, children involved in atrocities (including terrorist attacks). It explains the rationale for the book, noting that states have discretion to prosecute children but that there are various minimum standards, contained primarily in the Convention on the Rights of the Child, that must be upheld. These standards are binding in respect of all states that have ratified the treaty, yet post-conflict states often face significant reconstruction challenges. What, then, are the implications where states decide to prosecute minors for atrocity crimes? The chapter also introduces the role that international actors can play in enhancing implementation of, and compliance with, international standards, noting in particular UNICEF’s role as the lead UN agency for children in conflict with the law. The chapter notes the contribution of the book to existing scholarship and outlines the multidisciplinary approach, assumptions and methodology of the study, which includes semi-structured interviews and archival research, institutional and doctrinal analysis, and grounded theory and process tracing approaches. It also discusses the limitations and challenges involved in empirical research.