The book provides an up to date and authoritative account of how the UN is re[1]thinking its obligations to protect civilians during conflicts. Based on hundreds of interviews with senior UN officials and humanitarian protection staff in headquarters and in the field and a review of the UN's 'grey literature'. It also draws on the author's own experience of working on human rights and protection in some of the world's most violent conflicts. It is written not about what the UN ought to do - or how it could have behaved differently in an abstract or theoretically ideal world - but what the UN is actually doing to fulfil the fundamental purposes set forth in its Charter.