This article analyzes the main investigative and legal challenges addressed by the Acknowledgment Chamber of the Colombian Special Jurisdiction for Peace (SJP) in Case 07 on recruitment and use of children in the armed conflict. First, it presents a general background on the mandate of the SJP as a special system of justice – the outcome of the 2016 Final Peace Agreement reached between the Colombian government and the former FARC-EP guerrilla group. Second, it outlines how the investigative methodology used in Case 07 addressed challenges related to understanding child recruitment as a complex criminal phenomenon, the identification of those bearing the greatest responsibility, and the approach to the broad scale and scope of the victimization. Finally, the article addresses the main challenges faced by the Chamber in the legal qualification of the criminal patterns identified, and how it resolved three key issues: the determination of the age threshold under which child recruitment constitutes a war crime, the definitions of the international humanitarian law status of protections of individuals within an armed group, and the classification of different forms of gender-based violence as war crimes.