One of the main purposes of our studies of U.S.-based multinational firms has been to examine the relationship between direct investment by U.S. firms and the export trade of the United States, a subject of bitter controversy for at least the last fifteen years. Changes over time in trade flows and trade balances are influenced by trends in productivity in the United States and elsewhere and by shifts in monetary and fiscal policy, all of which ate reflected in price and income changes, the effects of which on trade probably swamp any that might stem from changes in the level of direct investment, One way to disentangle some of these influences might be to disaggregate by country, industry, and even better, by firm. However, we have not yet developed enough disaggregated time series data for this purpose and have therefore chosen to work with cross-sections by country and industry and, in some eases, by firm.