Nonreciprocal trade preference programs originated in the 1970s as an effort by high-income developed countries to provide tariff concessions for low-income countries. This study analyzes detailed trade and tariff data for the United States and the European Union (the two largest nonreciprocal preference donors) to determine the extent to which the programs have increased exports from beneficiary countries. The analysis finds that the programs offer significant benefits for some countries, mostly the higher income developing countries. Economic benefits in the least developed countries have been modest.