More than 300 child soldiers have been released by armed groups in South Sudan, the second-largest release since civil war began five years ago.
The United Nations calls the ceremony for 87 girls and 224 boys the first step in a process that should see at least 700 child soldiers freed in the coming weeks.
The head of the U.N. mission, David Shearer, says putting down weapons and rejoining normal life is just the "beginning of the journey."
One 17-year-old who was abducted says he was told to shoot his mother but the gun jammed and she escaped.
More than 19,000 children are thought to have been recruited by all sides since fighting broke out in 2013. The U.N. has released almost 2,000.
Human rights groups say child recruitment continues.