What is a "child soldier"? Expand “Child soldier” is a shorthand term for any girl or boy below the age of 18 who is recruited or used by an armed force or armed group, in any capacity. This definition follows the 2007 UNICEF ‘Paris Principles and guidelines on children associated with armed forces or armed groups’. It refers not only to children who participate in fighting but also those used as cooks, porters, messengers, spies, suicide bombers, or for sexual exploitation. It also includes children recruited and trained for military purposes but not used in war.