"Critics of globalization claim that firms are being driven by the prospects of cheaper labor to shift employment abroad. Yet the evidence, beyond anecdotes, is slim. This paper focuses on the labor market decisions of US multinationals at home and abroad for the years 1977 to 1999. Using firm level data collected by the US Bureau of Economic Analysis (BEA), we separately estimate the impact on US manufacturing employment of affiliate activity abroad, imports and exports within multinational firms, and technological change. We begin by reporting correlations between US multinational employment at home and abroad. Evidence based on the operations of US multinationals suggests that the sign of the correlation depends upon the crucial distinction between affiliates in high-income and low-income countries. US employment and employment in low-income (high-income) countries are substitutes (complements). The complementarity is driven by an overall contraction in manufacturing employment both in the US and in affiliates based in high-income countries. We then develop an empirical framework which allows the firm to determine employment at home and abroad simultaneously. Using a variety of different theoretical approaches to estimating labor demand and a range of econometric techniques, we find that employment in low income countries substitutes for employment at home. Employment in high income affiliates, however, is generally complementary with US employment. Second, US capital investments in both high and low income affiliates are associated with lower employment in the United States. Finally, our results show that other factors have made important contributions to falling manufacturing employment in the United States, including technological change and import competition. Taken together, our results suggest that concerns over the impact of globalization on US jobs are grounded in reality"--National Bureau of Economic Research web site.