The authors of this timely review work for the Centre for Health and Human Rights at Harvard University and the WHO Collaborating Centre for Research on the Epidemiology of Disasters at the University of Louvain. They draw attention to the massive scale of humanitarian crises due to natural disasters and armed conflict. They note that the immediate response to these crises has improved in recent decades with the development of standardised methods for rapid assessment of needs. These data have informed a needs-based approach to short term response but also the planning of subsequent bridging actions to give support in post-conflict/post-disaster settings. Systems such as the Standardized Monitoring and Assessment of Relief and Transitions (SMART) provide data that help assess the severity and need for emergency relief. These data also guide planning to improve resilience and preparedness for future events and to improve the effectiveness of responses to future crises.