Development and political actors are expanding their capacity to mobilise, coordinate and disburse resources, as well as set the policy framework for interventions in protracted crises. Humanitarian actors can ill-afford to ignore these major changes. In particular, they need to communicate clearly and fully the distinctiveness of their modus operandi and experience in these environments, and work with development actors to explore common ground. This paper examines how the international development aid system is becoming increasingly engaged in situations which, for many years, have been seen as largely the preserve of the humanitarian community. It reviews the changing relationship between the ideas, instruments and financing of the humanitarian system and of mainstream development cooperation in situations of protracted crisis.