This ODI Opinion reflects on the impact of 9/11 on the aid, development and security landscape and explores how development and security concerns merged in a new lexicon (‘fragility’, ‘radicalisation’, ‘stabilisation’). This raised hopes for development approaches that might better combine action to assure the human security of poor people with orthodox social and economic development. It also, however, raised fears that the ‘securitisation’ of aid would undermine both development and humanitarian action.