This Economica Coase Lecture reviews research that has revolutionized the field of international trade and foreign direct investment. It explains the motivation behind the development of new analytical frameworks, the nature of these frameworks, and the empirical studies that sprouted from them.

We develop a neoclassical trade model with heterogeneous factors of production. We consider a world with two factors, labor and "managers", each with a distribution of ability levels. Production combines a manager of some type with a group of workers. The output of a unit depends on the types of...