For decades governments, politicians, and trade unions have feared that firms investing abroad involved a loss of employment and a decline in wages for the home country, the implied assumption being that global production and consumption are somehow fixed. Similarly, research on multinational firms has tended to present them as having a number of alternatives - export, licensing or foreign direct investment - for the exploitation of fixed foreign markets.In reality, the complex relationships between parent companies and their foreign affiliates must be examined very carefully and with the most disaggregated statistics available if we are to get an accurate understanding of firms impacts. A major obstacle to this research has been the confidential nature of the necessary data. This collection, with contributions from many distinguished writers in the field, presents work which has been able to exploit relevant data for countries such as the United States, France, Italy, Belgium and Japan.