The index is based on the ratio from dividing the wealth of the best off 10th of the given society (a number which can exceed 100 percent if accounting for external sources of income) by the lowest 10th. The larger the number the greater the disparity of wealth. You can see where the United States stands in this small comparison. LDC (lesser developed countries) and emerging industrial nations may have large indexes as well. See Wikipedia's site on the Gini index for more information. http://en.wikipedia.org/wiki/Gini_index (Note: these numbers appear to have been multiplied by a factor of ten making them easier to read--a real factor would be between 0 (perfect equality) and 1 (perfect inequality. Again, see wiki.)