Disasters are very common occurrences, becoming increasingly prevalent throughout the world. The number of natural disasters either affecting more than 100 people or resulting in a call for international assistance, increased from roughly 100 per year worldwide in the late 1960s, to over 500 per year in the past decade. Population growth, environmental degradation, and global warming all play parts in accounting for these increases. There is also the possibility of a pandemic. This paper and associated journal issue focuses on the topic of growing worldwide importance: mental health needs assessment in the wake of large-scale disasters. Although natural and human-made disasters are known to have substantial effects on the mental health of the people who experience them, research shows that the prevalence of post-disaster psychopathology varies enormously from one disaster to another in ways that are diffi cult to predict merely by knowing the objective circumstances of the disaster. Mental health needs assessment surveys are consequently carried out after many large-scale natural and human-made disasters to provide information for service planners on the nature and magnitude of need for services. These surveys vary greatly, though, in the rigor with which they assess disaster-related stressors and post-disaster mental illness. Synthesis of fi ndings across surveys is hampered by these inconsistencies. The typically limited focus of these surveys with regard to the inclusion of risk factors, follow-up assessments, and evaluations of treatment, also limit insights from these surveys concerning post-disaster mental illness and treatment response. The papers in this issue discuss methodological issues in the design and implementation of post-disaster mental health needs assessment surveys aimed at improving on the quality of previous such surveys. The many recommendations in these papers will hopefully help to foster improvements in the next generation of post-disaster mental health surveys.