Better data is crucial to protecting “children on the move”, a diverse group of young people impacted by migration and displacement, both within and across borders. Existing frameworks emphasize the importance of data in upholding children’s rights, but current data collection methods have significant limitations. Vast differences in how governments collect data lead to inaccuracies, and many children on the move are simply not counted. This brief from IDAC delves into the data gaps surrounding children on the move and highlights best practices for improvement. It provides a vital resource for researchers, policymakers, and advocates working to ensure a brighter future for all children.