Migration is considered one of the defining global issues of the early twenty-first century, as more and more people are on the move today than at any other point in human history. There are now about 192 million people living outside their place of birth, which is about three per cent of the worlds population. This handbook will be the first to bring together both internal and international migration in the same publication. The first part on improving available theory will include interdisciplinary perspectives. Internal and international migratory movements have much in common, yet "theory" (or conceptual treatments) has proceeded on separate tracks for the most part. Therefore the first part of this handbook will attempt to bring these together. The second part will include data and methods for migration study. Part three will include regional perspectives of migration, whereby internal migration, international migration, and immigration will be described with balance as appropriate for the region. The last part will describe emerging policy topics in population redistribution and a conclusion will bring all of these topics together.