The mosaic effect: the revelation risks of combining humanitarian and social protection data Format Jill Capotosto As the world faces more frequent and intense crises---driven in part by *climate change, political and social conflict, disease outbreak---humanitarians are working to protect vulnerable people beyond the initial shock of each new emergency. While coordinating efforts between humanitarian programmes and social protection systems may help support individual and community resilience, it also creates the risk of new threats to data protection. **In this post, ahead of the ICRC Digitharium's 'Digital Dilemmas' virtual debate on social protection systems, Jill Capotosto from the Yale Jackson Institute for Global Affairs reviews one of the key data protection concerns of combining -- or 'mosaicking' -- humanitarian and social protection data systems: the risk of revealing new information, or 'data revelation'. Particularly in fragile environments, the unintentional revelation of new information may expose both beneficiaries and humanitarian organizations to unanticipated harm.*