This study systematically examines the distribution of the wealth of nations and how it has evolved over time. A nation's wealth is measured by its real per-capita gross domestic product. The study documents the following key economic development facts that a theory of economic development must be consistent with: There is a great disparity in wealth between the richest and poorest countries. This disparity has changed little in the postwar period. There was an upward shift in the distribution of the wealth of nations. There has been considerable relative wealth mobility, with some spectacular changes for individual countries in the distribution.