One of the reasons why child marriage in humanitarian settings continues to persist is a significant lack of data. The complex and often under-resourced humanitarian environments present a number of barriers to addressing this issue, even as humanitarian actors continue to flag this critical problem. This paper analyzes the current evidence and knowledge base on child marriage in humanitarian settings to see why such data gaps persist. It proposes recommendations for enhancing current data collection tools, analysis, and use in order to effectively address the issue through prevention and response efforts.