The impact of climate change on population mobility is a major global concern. This introductory chapter gives an overview on developments in research related to the linkages between climate and environmental change and human mobility that have evolved considerably since its beginnings in the mid-1980s. Despite the progress in research, the linkages between slow-onset environmental changes and migration remain unclear. This chapter highlights the challenges and consensus within environment-migration research and explains the alternative approach offered in this book. The approach focuses on individual capabilities and aspirations for migration in order to understand why some people migrate and others stay in areas affected by environmental change and contrasts it with the prevailing view that depicts migration mostly as a household adaptation strategy in response to environmental change.