Little is known about resettlement after disasters, although research on broader types of resettlement is not new. Despite there being some studies on post-disaster resettlement, the majority of them focus on short-term response, but not long-term recovery. Meanwhile, the number of people displaced due to environmental change, best exemplified by disasters, continues to rise. This dissertation introduces the concept of post-disaster 0́−resettlement0́+ as the process of permanent relocation following initial post-disaster displacement. Such displacements make communities face decisions over restoration of their livelihoods. One of the major decisions that communities encounter is between relocation and return 0́3 a decision between the opportunity of starting a new life in a new location or sustaining their pre-disaster livelihood. In disaster-affected areas, local governments also face a similar dilemma: whether to support relocation or repopulation, based on consideration of future vulnerabilities and inefficiencies of communities and regions. This dissertation targets two districts in the Nijumurago area of Japan that was devastated by the 2004 Chuetsu earthquake, to understand resettlement dynamics after large disasters. The target area provided a unique opportunity to study post-disaster resettlement comparatively, as two similar districts governed by different cities were provided with distinctive resettlement programs 0́3 one to relocate and the other to return. For in-depth study, five communities were selected to represent relocated, returned, and disintegrated communities for each. By observing these districts and communities, I aimed at unpacking the complex dynamics of resettlement from three conceptual dimensions of resettlement decisions, influence of planning processes on the resettlement decisions, and post-resettlement outcomes. I sought to identify key planning elements that lead to successful resettlement, by assessing the findings of three conceptual dimensions on decisions, planning processes, and outcomes. This study identifies several notable characteristics of post-disaster resettlement. First, post-disaster resettlement is a dynamic that develops based on the inherent characteristics of the affected areas. Because of this, plans and policies provided to communities by the governments or planners are often disregarded. In particular, resettlement programs designed to achieve their aim primarily by means of financial incentives are not always likely to succeed, because households have other competing goals; financial incentives are most influential for those who are most in need. Communities and households are therefore the key players that determine the decisions and outcomes of post-disaster resettlement. Second, however, actions by local government that set the speed of resettlement planning have a large influence on resettlement decisions and outcomes. For example, slower actions involving more deliberate decisions, despite increasing stresses and anxiety during displacement, seem to achieve better results and increased satisfaction in the communities after resettlement. Lastly, although neither relocation or return is inherently the best answer for all cases, collective community resettlement is likely to be more sustainable than disintegrated resettlement, in which community households all come to different resettlement decisions. Furthermore, careful deliberation under a longer-term vision seems critical to achieving resettlement outcomes that are sustainable. Overall, this research also has made several contributions toward a theoretical understanding of post-disaster resettlement. First, the research suggests a new notion of 0́−event-triggered resettlement0́+ that has characteristics distinctive from both forced and voluntary resettlement. Second, it contributes to add details to two well-known models of post-disaster housing and resettlement. And finally, the research suggests thinking about the second generation of households in recovered communities, in order to assess the sustainability of resettlement.