Previous research has been inconclusive as regards the effect of outward foreign direct investment (FDI) on domestic investments. In this article we show that this inconclusiveness can be explained at a disaggregated level as a function of the way industries are organized. Based on a simple model including monitoring and trade costs, we argue that a complementary relationship can be expected to prevail in vertically integrated industries, whereas a substitutionary relationship can be expected in horizontally organized production. The empirical analysis confirms a significant difference between the two categories of industry as regards the impact of outward FDI on domestic investment. The results may thus have profound policy implications.