This Handbook was published as part of the Brussels Privacy Hub and ICRC’s Data Protection in Humanitarian Action project. It is aimed at the staff of humanitarian organizations involved in processing personal data as part of humanitarian operations, particularly those in charge of advising on and applying data protection standards. The Handbook builds on existing guidelines, working procedures and practices established in humanitarian action in the most volatile environments and for the benefit of the most vulnerable victims of humanitarian emergencies. It seeks to help humanitarian organizations comply with personal data protection standards, by raising awareness and providing specific guidance on the interpretation of data protection principles in the context of humanitarian action, particularly when new technologies are employed. This second edition updates the text of the first edition and provides additional guidance in the following areas: digital identity, social media, blockchain, connectivity as aid, artificial intelligence and machine learning.