T he so-called "new trade theory" and more recently the literature on "geography and trade" have greatly enriched economists' understanding of trade. In the new trade theory, trade and gains from trade can arise independently of any pattern of comparative advantage (as traditionally understood) as firms exploit economies of scale and pursue strategies of product differentiation in an imperfectly competitive environment. The literature on geography and trade is a natural extension of this line of research, focussing on how industry agglomeration and regional differentiation can arise endogenously as a consequence of transport costs, market sizes, and the trade policy regime.These newer streams of literature are very limited in their treatment of firms. In these models, a firm is generally synonymous with a plant or production facility; that is, a firm is an independent organization that produces one good in one location. Multiplant and multiproduct production, whether horizontal or vertical, are generally excluded from the analysis. This is potentially troubling. After all, industries characterized by scale economies and imperfect competition are often dominated by multinationals. As a result, the policy and normative analysis that comes out of the new trade theory may be significantly off base. For example, conclusions of the "strategic trade policy" literature are fundamentally bound up with the notion of clearly defined national firms competing via trade with the national champions of other