A motivating premise of this book is that there are large economic gains to be had from greater international migration, particularly that from poor countries to rich ones. The book sketches the sources of those gains and analyzes some of the national political factors that militate against realizing them. Trachtman, a professor of law at Tufts University, examines several measures to overcome these barriers. One is to impose a tax on migrants, whose revenue would be shared by both the source and the destination countries. This tax would cover part of the educational investments the source countries had made in the migrants and part of the fiscal demands they were expected to impose on their countries of destination (beyond what would be covered by the taxes they would have to pay there anyway). Another idea involves formal international agreements that would liberalize migration under stipulated conditions. Although the book goes into considerable detail about the treatment of migration under existing multilateral and bilateral agreements, including within the European Union, it does not evaluate the consequences of those agreements. To get the ball toward liberalization rolling, Trachtman sketches what an international agreement on migration might look like.